Dougal Drummond scaled the last stile on the twenty mile hike as easily as he scaled the first, and his backpack was only lighter by two picnic meals and a flask of coffee. Sandy McCoy was struggling by now to keep up with his ex-soldier lover. He paused at the top of the fence and looked down the glen.

“Is that our hotel?” he asked. “That tiled roof over there?”

“Yes,” Dougal answered him. “That’s Tighe Meiklie. Only a mile away now, give or take.”

“A mile!” Sandy groaned. “Couldn’t you… you know, pretend I’m wounded in action and carry me on your back. If I was a comrade behind enemy lines in Iraq you’d do it.”

Dougal laughed.

“That would be cheating.”

“Next time we want a long weekend away from Glasgow, let’s go to a spa hotel and relax by the climate controlled indoor pool,” Sandy suggested. “I’m too old for this outward bound stuff.”

“This was your idea,” Dougal reminded him. “A peaceful country hotel with fantastic views, long rambles, just the two of us, home cooked food waiting for us when we get back.”

“I was deluded… about the rambles, anyway. I have to admit Mrs Bailie’s cooking is fantastic. Last night’s dinner – the breaded salmon was beautiful. That woman can make a fish glad to have been hooked. I hope it’s on the menu again tonight.”

“Not for me,” Dougal responded. “I’ve never been keen on fish. I used to hate the way they cooked it in the army. It looked and tasted like stewed knitting.”

Sandy laughed. They held hands as they made their way down an easy slope to the bottom of Glen Urquart and followed the placid river Enrick down to where it opened into Loch Meiklie. The air was pleasantly scented with the smoke of a turf burning stove in the kitchen of Tighe Meiklie. Supper was cooking. It spurred them on to the last leg of their journey.

“Good evening, Mrs Bailie,” they called out as they wiped their feet on the doormat in the hallway. The lady of the house stepped out of the kitchen, wiping her hands on her apron and smiled warmly at them.

“I’ll be serving in a half hour - just time for the two of you to freshen up. There’s fish or steak tonight. What will it be for you?”

“Steak for me, please, Mrs Bailie,” Dougal requested. “Medium rare.” Sandy asked for the fish and was told it was freshly caught in the loch this afternoon by Mr Bailie. Then they headed upstairs to shower and change.

“Does Mrs Bailie GET that we’re a gay couple?” Sandy asked as he stepped into the en-suite shower cubicle with Dougal. “She acts as if we’re brothers or something.”

“We booked a double bed, and she’s been in and turned down the sheets some time today, so I suppose she must have realised. But if it suits her to pretend we’re brothers, let her be. Our city sophistication is too complicated for her mind.”

They embraced under the cool shower before emerging to dry off and dress in casual slacks and t-shirts. Suitably clothed they headed downstairs to the dining room of the private hotel. They were in time to order drinks from the bar and choose a table by the wide picture window overlooking the loch while the dining room filled with the other weekend guests. These were mostly rambling or fishing people, mostly middle class, middle aged couples. They had spent the day out enjoying their leisure pursuits and now they were hungry for the evening meal. Good natured chatter rose to an ambient level as the soup course was served by Mr Bailie. It was home-made cress soup with fresh bread rolls.

Dougal’s steak for the main course filled three quarters of the dinner plate. The vegetables and potatoes vied for the remaining space. It was cooked exactly as he liked it. He savoured the taste and texture and watched his lover take a bite of the fish that took up almost all the space on his plate. It had white flesh beneath a silvery skin, in contrast to the pink steamed salmon of last night. It was served with a coriander sauce and a slice of lemon that Sandy squeezed over the fish to add to the flavour.

“What kind of fish is it?” Dougal asked purely out of passing interest.

“I’m not sure. The taste is… unusual. It’s stronger than trout or bass, slightly sweet. Good texture. It’s very much like a white version of salmon. I like it.”

“It seems to be going down ok with everyone who ordered it,” Dougal noted, looking around the dining room to see at least half of the guests enjoying the fish. Several of the men were having the steak option and there were four ladies who eschewed both in favour of a vegetarian lasagne.

“It’s a very good steak,” he added. “You don’t know what you’re missing. Food for a red-blooded man!”

“And you ought to learn to appreciate a freshly caught piece of fish. It’s got Omega 3 in it.”

“I always thought that was a cat food,” Dougal teased.

Their conversation remained light through the main course and the freshly baked apple pie and cream for dessert. They lingered, as many of the guests did, over coffee afterwards. Most of the guests withdrew eventually to the lounge where they settled to watch television or play cards and dominos until bedtime. Dougal and Sandy went for a walk by the loch.

“I really don’t GET the appeal of angling,” Sandy admitted as they walked past a fly fisher with his equipment. There were a half a dozen or so of them dotted around the loch in the warm and still bright evening. The most hardy of them would still be there with long life batteries in their torches when the sun went down about ten o’clock.

“Me, neither,” Dougal agreed. “Though I suppose Mr Bailie’s efforts must help with the food bills at the hotel. I can see the point of that. But as a sport, a pastime, I don’t get it.”

They walked on quietly until they drew close to the next angler. Despite their lack of interest in the sport of angling they stopped and stared at the fish that had just been pulled from the loch.

“What the bloody hell is that?” Dougal asked. “It’s enormous.”

“I have no idea,” the angler said. He dropped the fish into a bucket of water beside his folding chair. There was a small trout in there already. Or there was until the new fish turned around and swallowed it whole. The angler was startled by the ferocity of it. Dougal and Sandy watched the fish flop around in the bucket that it very nearly filled. They saw it open its mouth once and noted that it had a lot of small, sharp teeth.

“I’ve never seen anything like that in these parts,” the angler added. “It looks like a sea bass, apart from the teeth and those dark lines around the gills. But you don’t get sea bass this far inland - especially not in Loch Meiklie. It’s upriver from Loch Ness. That’s as far as any salt water fish would ever get.”

The angler leaned over the bucket as he spoke, his hand close to the water as he pointed out the lines around the gills and other features that distinguished this fish from anything he had caught before.

The fish leapt, its tooth-filled mouth open. Dougal reacted in time to save the angler’s hand, pulling him away and kicking the bucket over. The fish floundered on the grassy river bank and gasped helplessly in the air. Sandy pushed it gingerly with his foot and it rolled back into the water where it quickly swam away.

“Sorry about that,” he said. “The one that got away.”

“It can bloody well get away,” the angler answered. “I’ve never had a fish try to bite me back before. Bloody hell!”

The angler started to put his tackle away. He had obviously had enough for one evening. Dougal and Sandy headed back towards the hotel.

They came in through the side gate and grinned as they watched Mrs Bailie’s three cats tucking into a large plate of boiled fish heads and tails. The cats were enjoying their meal. Their combined purring was almost as loud as a motorbike engine ticking over.

“Those fish heads look like a smaller version of that big bugger your man caught,” Dougal commented. Sandy looked closer and agreed. The cats meowed their annoyance at having humans analysing their supper. They moved on into the house through the side door by the kitchen.

“I wonder if there were any fish left?” Dougal speculated, looking into the now quiet kitchen.

“Why? Did the cats’ supper make you hungry for a bite?”

“I just wondered what it was you ate tonight,” he answered, slipping into the kitchen and opening the big fridge. There was a drawer at the bottom. He pulled it out and saw two large fish, though neither of them as large as the one that had nearly bitten the hand off the angler. Even so it was obvious they were the same breed. The dark lines around the gills, the wedge shaped dorsal fin that the angler had also drawn attention to….

….And a mouth full of small, sharp teeth.

“Can I help you lads?” Mr Bailie stood in the kitchen door. “We don’t usually encourage guests to go into the fridge, but my Annie has a bit of a soft spot for the two of you. If you need a snack I dare say she’ll fix you up.”

“No, we’re all right,” Dougal told him. “We just wondered. What sort of fish was it that you served up at supper tonight? I’ve seen nothing like it before.”

“Can’t say I have, either,” Mr Bailie answered. “But it came out of the loch, there, so it can’t be anything dangerous.”

“Depends on your definition of dangerous,” Sandy told him cryptically, thinking about the near miss with the angler. “I guess it must be all right. I ate it, and I’m fine. But it might be better if you don’t serve unknown fish to your guests in future. If somebody was to complain to the Food Standards Agency….”

“I hadn’t thought of that,” Mr Bailie admitted. “It’s a pity. They’re so big half the guests were fed with the fillets taken from three fish, and Annie said they cooked so beautifully.”

“Never mind - Sunday tomorrow. Roast beef and Yorkshire pudding should be safe enough. We’ll bid you goodnight, Mr Bailie.”

Some of the guests were still in the lounge playing a card game of some sort. Dougal wished them goodnight cheerfully as he and Sandy mounted the stairs and headed up to their room.

Of course, they made love. That was the point of a weekend away. Sex in a different bed, with the window open and the sounds of the countryside drifting in with the balmy breeze instead of the noise of the city was extra sweet, extra special.

Extra vigorous. Dougal was surprised just how pro-active Sandy was. Usually he played the passive role in their love-making, but tonight he was very different. Not that he was complaining. It was incredibly hot stuff and he enjoyed it, even if he felt afterwards as if it had been half sex and half wrestling.

“I think I’m actually bruised,” Dougal commented as they lay together in the warm, perspiration-scented aftermath. “You were wild tonight. What came over you?”

“I don’t know. Fresh air and exercise, I guess,” Sandy answered. “I’m exhausted now, though.”

“Sleep well, sweetheart,” Dougal told him. He turned sideways with his arm across Sandy’s chest and prepared to sleep.

Moments later he was shaken awake by the sound of a vicious cat fight outside. He jumped from the bed and looked out of the window. He couldn’t see much in the dark, but it looked as if the fur was literally flying.

“Mad moggies,” he said, turning from the window.

Then there was a scream from downstairs. It was a woman’s voice and she was terrified. Dougal grabbed his trousers from where he had discarded them and pulled them on before heading downstairs. Sandy took a little longer to put on a shirt as well as his trousers and follow him down.

When he reached the lounge he was astonished to see two of the guests, Mr Henry and Mr Anderson, lying among the debris of their domino game with their arms tied behind their backs with the sashes from the curtains and with handkerchiefs stuffed in their mouths to keep them quiet. Dougal, meanwhile was separating two women from the card game who had attacked each other with butter knives. He was trying to be gentlemanly about it, but the women were slashing at him with the knives and he had to avoid the wrath of both while disarming them.

Two men, the husbands of the two women, were sitting on the floor nursing butter knife cuts to their abdomens. Sandy grabbed the mandatory first aid kit from the dresser and attended to them. None of the cuts were deep, and the men were in shock more than anything.

Dougal manage to restrain the two women. He was no sooner done, however, when another of the guests, Mrs Hallam, ran down the stairs in a very short, frilly nightdress, pursued by a soap-sud covered but otherwise naked Mr Hallam who was brandishing a bathroom loofah in a threatening way.

“What the hell is the matter with everyone in this place?” Dougal asked as he disarmed Mr Hallam and tied him up with the last of the curtain sashes. One of the guests found a travel rug that they covered his blushes with as the soap suds dissolved.

Moments later Dougal and Sandy both ran to the private drawing room where Mr and Mrs Bailie were throwing prized china ornaments at each other while screaming in rage. They, too, had to be restrained physically before they could be calmed enough to walk them into the main lounge with the others.

“I repeat,” Dougal said. “What is the matter with everyone in this place?”

“Not everyone,” said Mr Sweeney, one of the stunned onlookers. “I don’t know what came over them, but it didn’t affect me.”

Three other men and two women admitted that they had not given in to angry outbursts and confessed themselves perplexed about what happened.

“They just started to argue about the domino game,” Mr Sweeney said about the first two protagonists. “And Mrs Hamilton accused Mrs Ronson of ‘making eyes’ at Mr Hamilton.”

The others agreed that this had been the start of the two most vicious rows.

Dougal looked around at the group of hotel guests and their now quite contrite hosts. He reached to undo the restraints on the two domino players. The fight had gone out of them now and they sat quietly, holding hands. That surprised everyone except Dougal, Sandy and Mrs Bailie who made up the beds, after all.

Sandy unbound the two ladies and Mr and Mrs Bailie and told them all to sit down for a moment. He seconded two of the unaffected people to come to the kitchen and help him make tea for all.

“That’s what we need right now,” he said to the silent group who were either too shocked, embarrassed or utterly perplexed to argue. “A good cup of tea.”

While the tea was brewing something occurred to him. He went to the laundry room that was separate to the spotlessly clean kitchen where meals were prepared for guests. The three cats had a basket in there next to the tumble dryer. They formed a homogenous mass of fur with eyes, ears and tails now, but it wasn’t so long ago that they had been fighting each other. He bent and picked up one of the cats and saw a large chunk of fur ripped out of its side. Another had the tip of its tail bitten off and the third had a cut right above its eye. He carried the basket of cats into the lounge and used what was left in the first aid kit to treat their wounds while the tea was being distributed.

Dougal glanced at the cats and realised the same thing that Sandy had already worked out.

“It was the fish,” he said. “Everyone who ate the fish suffered uncontrollable fits of irrational anger in some way. Even the cats. At least….” He looked at one woman sitting quietly in the corner. She looked away from him sheepishly. “Miss Darnell, isn’t it? I’m sure you ordered fish at dinner.”

She looked up at him. Dougal noted that she was a very thin woman with a pale complexion.

“You’re bulimic?” he guessed. She nodded and hid her face again. “You went to the bathroom after dinner and vomited it all up.”

Again a nod.

“You need to go and see somebody about that,” Dougal told her. “It’s not good for you. But in this case you’re probably lucky. You weren’t affected.”

“Neither was I,” Sandy pointed out.

“You were aggressive enough in bed,” Dougal answered with an indulgent smile. The other guests and their hosts all looked shocked when they first realised what he meant, then they thought about it a little more.

“You mean….” Mr Henry ventured. “If we’d had an early night, instead of staying up playing dominos… we might have worked off the aggression with….”

Mr Henry blushed and let the sentence go unfinished. He was old enough to remember when his kind of love-making wasn’t so openly acknowledged. The heterosexual couples thought it through as well and realised that Dougal had a point.

“We’ve all been very foolish,” Mrs Hamilton admitted.

“You were all affected by something that made you act against your nature,” Dougal assured them all. “No permanent harm has been done, yet. But it’s time to call in the experts.”

“There are experts on this kind of thing?” Mrs Ronson asked.

“Not… the Food Standards Agency?” Mr Bailie queried in a worried tone.

“No,” Dougal answered as he reached for his mobile phone and called a present number. “Torchwood.”

“Who are Torchwood?” The question went around the room. Dougal didn’t enlighten anyone, but the cool, calm way that he ordered the containment operation around Loch Meiklie reassured everyone. The guests, led by Mr Henry and Mr Anderson took themselves to bed. Mr and Mrs Bailie waited a little longer. They had a reputation to uphold and it all sounded a little too official.

“It’s all right,” Dougal assured them. “Torchwood know how to be discreet. My boss is putting out a message to the media warning people not to eat our not so friendly fish. We’re using ‘dangerous levels of mercury’ as a reason. It’s nonsense, but people will believe it. Meanwhile the team will be here by six. They’ll do discreet tests around the Loch to find out where the wee beasties come from.”

“Six?” Mrs Bailie echoed. “All right. I’ll be up at half-five to make breakfast for them. Will bacon and eggs be all right?”

“I’m sure it will,” Dougal assured her. Satisfied with that Mrs Bailie and her husband took themselves to bed. Dougal and Sandy prepared to keep a quiet vigil in the lounge with a basket of wounded cats for company. Sandy slept on the sofa, just as he did when he stayed in the Hub on the graveyard shift. Dougal sat back in an armchair and let himself sleep four solid hours, waking himself just before dawn. He went out in the cool grey light and walked around the loch. Everything seemed quiet, but he knew that was deceptive. In the deepest part the loch was as much as forty-six metres deep and who knows what lurked down there.

Well, everything except a huge amphibious creature of legend. That lived in Loch Ness, downriver from here. But Loch Meiklie had some monsters of its own just now. Where they came from and how, the Torchwood team would doubtless find out.

He turned his feet back towards Tighe Meiklie. As he did, he noticed a bird, a gull of some kind, swooping down towards the still surface of the loch ready to snatch up a fish from the water.

Instead, the gull was snatched. Dougal suppressed a shocked yell as he saw one of the fish leap from the water, tooth-filled mouth open, and pluck the bird from the air. It splashed down into the water leaving a few bloody feathers floating in the centre of the concentric ripples of surface disturbance as the only proof that anything had happened.

The fish was at least twice as big as the one that had almost had the angler’s hand last night, which was considerably bigger than the ones Mr Bailie had caught earlier yesterday for the supper table.

They were growing exponentially.

By six o’clock the team might not have time to eat Mrs Bailie’s breakfast.

They called it a briefing instead. Owen, Munroe and Shona joined Dougal and Sandy in the dining room and ate bacon and eggs and an unlimited supply of toast and coffee while they set up all of the portable equipment they could fit into the back of the Ford Escape and went over the little information they had.

“There was a low level alert in this area two weeks ago,” Owen admitted when Mrs Bailie was out of earshot having gone to make more toast. “Munroe’s Loch Ness sensors picked up a brief trace of an ion-meisson burst. We know that usually indicates a UFO using hyperdrive engines, but it lasted less than a minute. It didn’t seem worth coming up to look. Could be I made the wrong call on that.”

“So these fish are alien?” Sandy asked.

Munroe looked at the laptop screen in front of him and nodded. He had already taken tissue samples from the fish in the bottom of the fridge.

“Absolutely alien,” he said. “I’m seeing chemical traces that never occur naturally on this planet.”

“Also levels of dopamine, norepinephrine and epinephrine that are off the scale,” Owen noted from his own laptop. “Those are the so-called ‘rage hormones’ that are increased in the blood-stream during periods of heightened emotion – especially anger or sexual arousal.” He glanced at Sandy, who blushed endearingly. “I’ll want to take blood samples from you and everyone else who was affected to see if there are likely to be any long term effects. I’m hoping that the flashes of rage that took place last night will have used up the extra hormones leaving them all embarrassed but normal this morning, but we’re better safe than sorry.”

“What about the loch?” Dougal asked. “It’s closed off now?”

“You wanted it low key,” Shona Stewart pointed out. “That rules out a military lockdown. We’ve posted signs warning of mercury contamination. If anyone is stupid enough to try angling or whatever then they deserve to get their legs bitten off.”

“I’ve got the loch monitored,” Munroe added. “The fact that these big alien fishies have so many unusual chemicals in them makes it easy to tell them from the indigenous species. Unfortunately, there aren’t so many of those left now. They’ve obviously been feeding on the grilse and trout and what have you. Pretty soon they’ll be the only fish left in Meiklie.”

“What then?” Sandy asked. “Will they starve?”

“No,” Munroe answered. “They’ll migrate looking for other food. And then we’ll have trouble. If they go upriver, it’ll be bad enough. They’ll ruin the salmon spawning. But if they go downriver….”

“To Loch Ness.”

“Won’t Nessie deal with them?” Shona asked. “The last time I was up there with Munroe she’d grown a lot… nearly as big as her mum was. She’ll make a lunch and dinner of them.”

“That’s the last thing we need,” Munroe said. “Nessie is a placid wee girl. She doesnae bother naebody.” As ever when he was in his rural element, Munroe’s vernacular became more Scottish. “If she gets a bellyful of these crabbits there’ll be nae knoin’ wha’ she might dae.”

When everyone else had translated his words the danger was clear. A Loch Ness Monster with the rage hormones boiling in her blood would be very dangerous, to say the least.

“And after Loch Ness, it’s straight on to the sea,” Shona pointed out. “If they can live in salt water, then we may be looking at a major ecological crisis. They’re clearly the top predator in the loch.” She glanced at Munroe’s monitor. In the time they’d been talking the stock of indigenous fish was distinctly reduced. It was all happening very fast.

“We need nets across the entrance and exit of the river,” Owen said. “Steel nets, strong enough to stop these stroppy buggers. Munroe, you sort that out. I’m going to start on those blood tests. Dougal, Shona, you go and wake up the neighbours. Mrs Bailie might not be the only one who cooked a fish supper. Let’s make sure there haven’t been any lethal domestics in the area. Sandy, you can help me out with the blood tests. The guests have met you and the landlady seems to have taken a shine to you, so it’ll smooth the way a bit.”

The boss of Torchwood Glasgow had assigned roles. Everyone went to do them. Dougal followed Shona outside to the car where she opened a compartment in the boot and took out two handguns, loaded them with magazines and passed one to him. He put a shoulder holster under his jacket and slipped the gun in place. Shona put hers in the back pocket of her slim-fitting jeans.

Checking on the neighbours might have seemed like a soft job to two experienced soldiers like Dougal and Shona, but it proved a necessary task. The closest neighbours to Tighe Meiklie were a group of log built holiday cottages. In two out of the three they found people nursing bruised bodies and even more bruised souls as they tried to work out why they had been fighting. In the third they found a honeymoon couple about to pack their bags and go their separate ways. The groom had a black eye and the bride had defensive wounds on her hands and arms. Shona discovered a skill she didn’t know she had before – as marriage guidance councillor. Dougal watched with a half smile as she persuaded the young couple that their night of violence was induced by a rare form of food poisoning and that they could give each other a second chance.

“Shut up, you,” she told Dougal as they moved on from the newly restored married bliss. “And don’t you dare mention that to Darius when we get back.”

Dougal put on an innocent expression as they called at a converted farm house where they got no answer at the front door. Dougal was about to shoot off the lock when Shona pointed out the former barn from which a loud noise was coming. As they drew closer the noise was recognisable as a very forceful style of rock drumming. They slipped in through an unlocked door into what had been fitted out as a private recording studio. They recognised the man who was working out his irrational feelings of rage on the drum kit. He was wearing a pair of jeans and nothing else. Sweat poured from his body as he created a rock thunderstorm with no more than a pair of sticks.

“I’ve definitely got to buy his new album,” Dougal said as they slipped back out again without interrupting him. “That’s some phenomenal sound.”

“Working off the rage with rock music,” Shona said. “That’s better than picking a fight with your mates, or aggressive shagging.”

Further round the loch things were not quite so creative. They came across two more private hotels where fish had been on the evening dinner menu. In both there had been inexplicable punch ups among the guests and the chef at the larger of the two establishments was still locked in the vegetable storeroom after wielding a carving knife at the manager. Shona and Dougal restored order and gave the agreed lie about mercury levels in the fish as the reason for everyone’s unusual behaviour.

“Oh no!” Shona murmured as they approached the last but one of the residences around the loch. They could both hear the sounds of cats – lots of cats. They found the ripped bodies of two tabbies who were beyond help near the gate. Around the back of the house was a man making a tiny grave for three more dead animals. He was crying.

When he stood up from his sad task even Shona gasped in shock. There was hardly a part of his face and arms that wasn’t ripped and bitten. Some of the wounds were deep.

“You need medical attention, sir,” Dougal told him. “Let us help you.”

“The cats,” he answered. “Some of them are injured.”

“We’ll look after them, too,” Dougal promised. “But let’s take care of you first.”

The man accepted their help. He told them his name was Keith Alexander and that he owned twenty-five cats, strays that he had adopted and nurtured. He broke down in tears as he described the night of horror as his pets turned on each other, and on him. When Shona explained what had caused the tragedy he paled with shock and then exploded with anger. For a moment the Torchwood pair thought he was another victim of the uncontrolled hormones.

“It’s that bastard up near the bridge,” he said. “Randall… he’s done something. Last summer he kicked two of my cats because they went near his bloody fish pond. He’s obsessed.”

Shona privately thought that a man who owned twenty-five cats was the proverbial pot calling the kettle when it came to obsession, but the fact that there was somebody with an interest in breeding fish in the area was worth knowing.

Mr Randall’s property was quite large and surrounded by a high fence and a locked gate. Dougal and Shona climbed the gate and approached the house. They couldn’t help noticing a very large ornamental pond by the path. It looked as if it might have once contained koi carp or some sort of outdoor fish, but now it just had one example of the predator fish. It was not as large as the ones they had found in the loch itself, but they had no doubt that it was the same breed. When Shona’s shadow fell across the pond it launched itself out of the water and snapped at the air with its sharp teeth.

“It hasn’t grown because it hasn’t got the space or the food supply,” Dougal noted. “It’s mates in the loch were top of a much wider food chain and they’ve got forty-six feet of water in the deeper part.”

They turned towards the house again just as the door opened and a man, presumably Randall, aimed a shotgun at them.

Shona and Dougal both pulled their automatic pistols instantly.

“Drop it, sunshine,” Dougal said. “We’re both better armed and way faster than you.” Randall continued to point the shotgun at them for several seconds before wavering and finally putting it down at his feet and raising his hands. Shona made the shotgun safe while Dougal encouraged Randall to move back into the house.

“Bloody hell,” he commented and remembered Mr Alexander’s comment about obsession. The open plan drawing room was one huge private aquarium. Tanks fixed one above the other covered all four walls, most of them containing multicoloured tropical fish. The colour and constant movement was almost hypnotic.

Almost. When Mr Randall took advantage of their distraction and lunged towards Shona, he underestimated her very badly. Moments later he was lying on his stomach with her slight figure crouched over him, his arms twisted behind his back and his face pressed against the carpet.

Fully satisfied that Shona had the man of the house under control Dougal gave his attention to the largest two tanks on the far wall. One of them was empty apart from a layer of reddish sand on the floor. The other contained another example of the predator fish.

“You’ve been trying to domesticate these fucking things?” he demanded. “Are you out of your mind? Shona, take your hand off his mouth or he can’t talk.”

Shona shifted her hold slightly. Mr Randall swore vociferously. She punched him in the mouth.

“Don’t talk that way in front of a lady,” she said, in the face of all evidence to the contrary. Dougal repeated his question.

“I’m interested in fish,” he answered. “Two weeks ago I was up early, just after a shower of rain. I found the garden full of these small blue jelly blobs like fish eggs, only bigger, like nothing I’d seen before. I gathered some of them up. It’s a good job I did. An hour later when the sun was full up the rest of them desiccated. They crumbled away into dust. But the ones I brought in… I didn’t know what sort of water they needed. I tried salt water, but they didn’t hatch. I tried them in the tropical warm water tanks, but that didn’t work, either. Then I noticed that there were new fish in my koi carp pond. So I tried hatching them in cold fresh water. I had Herichthys cyanoguttatus in that tank to begin with - Texas cichlid. But these fish killed them.”

“Nice,” Shona commented. “How come there’s only one of them, now? Did you dump the rest in the loch? Is this how they got in there?”

“I didn’t go near the loch,” Randall protested. “When they’d finished eating the cichlid’s, they turned cannibal. They fought each other and ate the dead.... until there was only the one left. Then I noticed that my koi carp were gone… and the fish in the pond did the same, cannibalising each other until there was only the one left.”

“So you only have the two specimens?” Dougal asked, just to be certain. “One in that tank and one in your pond?”

Randall nodded.

Dougal raised his pistol and aimed at the tank. He allowed for refraction and squeezed the trigger. The bullet went straight through the fish’s left eye and out through the right a fraction of a moment before broken glass, water and the stone dead fish spilled out onto the carpet.

“I’ll deal with the other one on my way out,” he added. “For the sake of your limbs, stick to a bowl of goldfish in future.”

He walked out of the house and shot the fish in the pond outside. Shona followed him.

“My jeans are wet, thanks,” she said. “Did you enjoy shooting the fish?”

“Not really,” Dougal answered. “They’re just animals. They can’t help what they are. But I couldn’t let that dickhead breed them.” He looked around the garden and thought about what Randall had said. “The fish eggs must have been dropped from the UFO that buzzed this area. The one we have on record. Whether it was a deliberate attempt to seed an alien species on this planet or the aliens didn’t fancy their caviar, I don’t know. Some fell on the land and dried up in the sun. Some fell in his carp pond where they were fruitful until the food ran out. But some of them must have fallen into the loch, perfect hatching conditions.”

“Sounds like the biblical thing with the sowing of the wheat,” Shona noted. “Anyway, we established that Randall is an idiot but he didn’t have anything to do with the ones in the loch. What do we do about them, now?”

“I wonder,” Dougal answered. He put his gun in his holster and touched his in-ear communicator. He contacted Owen and asked him a question.

“Fuck me!” Owen said when he found the answer to that question.

“I would, but your wife and my husband would kill us,” Dougal answered. “Am I right?”

“You’re absolutely right. The numbers of the predator fish in the loch are reducing since we damned off the river and isolated them. They’re eating each other.”

“Right.”

He closed the communication and strode off towards the lochside. He watched the surface of the water carefully. When he saw a ripple of movement he aimed his pistol. The shot echoed loudly. Fish blood and tissue billowed from the carcass of a fish nearly four foot long from head to tail. It was quickly the centre of a feeding frenzy. He fired again, killing a half a dozen more fish that immediately became food for others that flocked to the feast.

“How are those numbers now?” he asked Owen when he was out of bullets.

“They’re going down. But I don’t think you can shoot them all.”

“I won’t have to. If they continue to attack and eat each other, they’ll finish the job for me.”

“Dougal.” Munroe MacDonald’s calm voice spoke close to his ear, over Owen’s voice on the coms. “There is a school of thought that says we shouldn’t kill all of them. These are ugly beasties, it has to be said. But they’re a unique species just the same as our Nessie down the river. We shouldn’t wipe them out completely.”

Dougal reached out his hand. Shona Stewart passed him a fresh magazine for his gun. He carried on shooting at every tooth-filled silvery-grey head that he spotted just beneath the surface of the loch. He never missed. The water was turning red with the blood and brain tissue of the creatures he killed while those left churned it into a foam as they fed on the remains. It was a chillingly gruesome sight in what had been a peaceful loch until today.

“Do you want to start an aquarium for alien fish life? Dougal answered, finally. “Like that Randall twat over the way?”

“We don’t have to start one. Torchwood Cardiff has an aquarium fifteen floors beneath the Millennium Centre,” Shona answered. “Darius told me about it, once. Jack Harkness showed it to him. I think it was meant to be a sort of romantic ‘date’. The room is full of reinforced and pressurised fish tanks full of creatures that belong on the deep ocean floor, so far down that they would explode if exposed to the surface pressure. The tanks are the only place they can live outside of the ocean. Apparently some Torchwood employee in the eighties had a thing about ‘monsters from the deep’ and installed the facility. They maintain it because none of them know what the hell else to do with it.”

“So?” Dougal replied between shots.

“So, I think Jack might want to keep one of our fishies to see what happens to it long term,” Munroe said.

“These bloody things are lethal,” Dougal reminded him. “Not only do they make humans and animals who eat them turn into psychos, but they can KILL by themselves. Have you seen the SIZE of these bastards, now? They could bite a man’s head off. They can’t stay here.”

“Munroe, come with me,” Shona suggested. “Dougal, keep shooting. I agree with you about destroying them. Don’t get me wrong. And Owen is fully in support of you. But I think we might be able to accommodate Munroe’s idea as well.”

Dougal watched them go then whipped around and shot at a fish that was getting on for eight feet long, now. Owen said something about a super-accelerated metabolic rate. The survivors of his pogrom were growing by the minute.

Just how big could they grow? Was there a limit? Dougal was a largely practical man. He didn’t give way to daydreams as a rule, but visions of several killer shark films flashed through his mind and he let himself wonder just what he had let himself in for.

“You can shoot all of the little bastards now,” Shona told him. He looked around as she and Munroe returned. She was holding a cryo flask. “As I suspected, Randall didn’t use all of the eggs he collected. He kept some in his fridge. The low temperature kept them in hibernation. Jack can stick them in his aquarium and study them to his heart’s content. The species is preserved for whatever reason anyone would want to preserve it. But we can eliminate them from this loch before they kill somebody.”

Dougal turned back and looked at the water. It was surprisingly still. The feeding frenzy seemed to be over for now. He aimed his pistol but he couldn’t see another target.

“Owen, where are the little bastards?” he asked.

“Unless this scanner is playing up there’s only one great big bastard left and it’s gone into the deep water in the middle of the loch,” Owen answered. “The one that got away.”

“Not bloody likely,” Dougal responded. He watched the surface of the water carefully. Then he gave an excited cry and began to run along the side of the loch. There was movement. Something big was churning the water as it moved in a more or less straight line towards the place where Loch Meiklie emptied into the lower half of the river Enrick.

“Fucking hell!” Shona exclaimed as the loch grew shallower and she saw just how big the last fish actually was. “Dougal, you’re going to need a bigger gun.”

“No,” he answered with confidence. “I just need a clear shot at it.”

He knew exactly what was going to happen next. The last of the predatory fish in the loch was trying to get downriver to the much bigger food source of Loch Ness. The nets that had blocked the river wouldn’t stop it. They were only steel mesh, after all. But the river was only about eight feet deep at that point, and the fish was nearly that wide, now. Swimming with so little water around it would slow it down.

Dougal left the lochside and sprinted across the field next to the holiday cottages to the tree-overhung private road that served them. Munroe and Shona continued along the side of the water, losing sight of him until he appeared on the stone bridge that crossed the Enrick and joined the A831 on the other side. He lined up his pistol, using the bridge parapet to steady himself.

Shona found herself holding her breath. He really did only have the one chance to get the creature between the eyes, the one place that generally killed anything with a brain and a central nervous system.

Dougal fired twice in quick succession, the double tap of a skilled sniper. The fish jerked and thrashed in the water. He relaxed his stance, looking down at the dead creature that slowly bumped against the place where the stone arch curved down into the middle of the river.

“We need to get it out of there,” he called out to his colleagues on the bank below. “We don’t want other fish taking bites out of it and then getting aggressive at each other. We should burn the carcass. Then it’ll all be over.”

“There’s still the one from Mrs Bailie’s fridge,” Shona called back. “Sure you don’t want it in batter with a serving of chips?”

“I want steak, medium rare,” he replied. “And if I see so much as a packet of fish fingers in our freezer when we get back to Glasgow it’s going in the waste disposal.”