The Doctor went into his main store before he headed out of the TARDIS. He collected two torches. One with red light and one standard white torch. He also found his night vision goggles. He had to search for them for a moment as he'd popped them in with his swimming goggles and they looked almost identical.
He gathered twelve explosive charges. Six in each tunnel entrance should be sufficient to bring them down. They could be set to be detonated using a delay or with a remote trigger. He'd plan to set them to blow on a delay, but then if he was spotted or he had to make a rapid exit, then he could trigger the explosives. He put everything in a cloth sack and slung it casually over his shoulder. The sack and the equipment within it struck him in the back and he gasped. He was an idiot. He dropped the sack back from his shoulder and wrapped the end of it round his fist a couple of times. He'd just have to carry it that way.
How did he get himself into these kinds of messes? He was only supposed to be going to taste test the best hot chocolate in the galaxy to make sure it was good enough for Rose. Now there was a pack of alien reptile wolfie things killing people and dragging corpses down into limestone caves under North Yorkshire. More, he had a wary runaway fourteen year with a smashed ankle and powerful psychic abilities stashed in the TARDIS sickbay. He stretched up to get a spare power cell from the top shelf in the store and hissed. He also had three deep slashes through his back which were definitely doing their best to make sure he didn't forget them - he was fully reminded.
With everything he thought he needed he left the TARDIS and pulled the door closed behind him. Josh would be able to get out if he decided he wanted to, but nothing would be able to get in. He took a breath to centre himself to clear the vague headache that had remained since he'd been psychically hit in the vortex. He put the night vision goggles on and looked around the forest then set off down the path toward the storm drain.
He wondered if there was going to be any authority presence there. One of the older boys had escaped. He'd been running when he'd arrived. If he'd told anyone of his ordeal, and they had believed him, there might have been police in attendance. More people would be at risk and would they let him stroll into the dark to blow it up? There was no hint of anyone else as he approached.
The Doctor was glad he'd gotten out, but he didn't have any burning desire to go and check on him now he was safe. From what he had gleaned so far it was apparent they had attacked Josh and stolen his rucksack. They were a lot older and a lot bigger than Josh and there had been four of them — that was cruelty. He was sad the three had been slaughtered, he'd held one of them as they'd died and he'd do the same again, but he wasn't going to go out of his way to help the escapee since he was no longer in danger. He could learn his own lessons from it. Maybe seeing his friends get ripped to pieces by alien creatures was a harsher lesson than most, but it was still a lesson. Pick on the vulnerable - kids younger, smaller, and on their own and eventually you'll get eaten in one way or another — admittedly it usually wasn't quite as literally.
The night vision goggles gave him all the sight he needed as he headed back into the storm drain. He knew where the lair was now. He kept quiet, hugging the sides of the tunnel, but moved swiftly. There were no signs of the creatures in the tunnel leading toward the cave. Hopefully they hadn't all left to go hunting. He'd not thought to ask. Josh had said set snares to catch animals for food. If the creatures were hunters were there any native woodland animals left? Did Josh ever catch anything? He should have asked him. He'd ask him when he got back.
The Doctor continued to the lair. The bodies of the two teenagers he'd encountered in the tunnels were gone — dragged back into their larder to eat at their leisure. He inched toward the opening and looked down into it. Five of the animals were active in the bottom of the cavern, three of them appeared to be playing or squabbling with each other and two were feeding. On the ledge one of the animals was laying on its side. It pawed at its head and as the Doctor watched it raised itself up, shook its head back and forth, and then dropped back down. It was irritated. The Doctor guessed it was the one who had attacked him. Its ears still be ringing from a direct sonic pulse but it wouldn't have caused it any permanent damage. His back was still raging, stinging, and burning so he accepted that as fair play.
The three animals that were playing were pouncing and snapping at each other. They were much more alert than they had been earlier in the evening suggesting nocturnal inclinations. He didn't want to stay any longer than he had to even if it was fascinating to watch them dance around, snap, and skitter away from each other on top of their carpet of decaying corpses.
There weren't many flies. He thought there would be more flies with all that decomposing flesh. He didn't ponder that for long, because he wasn't sure what to do. He had a problem. There had been eight of them in the lair earlier and now there were six. Two of them were off somewhere else.
The Doctor backed away from the entrance to the lair and set six of the explosives in the tunnel. He only needed to collapse the tunnel. If he brought the roof of the cave down, if they didn't get killed, they would be able to get out and with their food source would be buried under a rockfall they might seek additional food. They clearly had a taste for human flesh so he needed to avoid that.
The Doctor wired the charges together so they would detonate in a rapid sequence. He set the timer on the central explosive to 5 minutes, but he didn't start the count down. He'd do that on his way out. He returned to the storm drain and went up to the tunnel that headed to the surface. He used the sonic screwdriver to unlock the padlock on the chain holding the rusted grille in place. The padlock was rusted solid - the lock unclicked but didn't open. He gave it a swift quick smack with the butt of his torch and it came apart. He pushed the grille far enough into the nettle bed behind it for him to be able to squeeze through - doing his best to avoid a nettle going up his trouser leg.
The Doctor used sonic to track his movement across the surface in relation to the lair. There had to be another way down to access the tunnel on the far side of the cavern. He moved cautiously through the trees, especially where there was thick undergrowth. There were still two creatures unaccounted for. He didn't want to happen across them or be ambushed, but he also needed to make sure he didn't seal them out either.
He found another abandoned drain cover. This one led into a vertical shaft. He removed the cover and slowly descended on the ladder before dropping down into the tunnel. It led into another large cave. According to his mental map of the area the lair should have been to his left, round a bend, and up slightly, but there was a strong stench of decay coming at him from down a tunnel snaking into darkness in the other direction. He crouched down in the natural cave. There was a shallow pool of carbonate rich water in the base. It was deep enough to soak his feet through his Converse.
The Doctor scanned the area with the sonic screwdriver, willing the tool to keep the noise down. There were three larger caverns deeper under ground. Sonic showed higher thermal energy readings than in the tunnels something in them was giving off heat. He needed to investigate. He set the sonic screwdriver ready to emit a sonic pulse if he had to. It had clearly affected the creature in the other cave long enough that it was still suffering.
He moved silently making sure every step was secure on the slick wet limestone floor. The natural tunnel he was in had been carved by water passing through the limestone rocks. Following heavy rain it must have plunged from the end and down into another cavern. The chamber floor was much two metres below the point the tunnel joined it. He crouched down, getting wet knees as well as wet feet, to peer through his night vision goggles. There were two creatures in there. He didn't know if they were the two that he'd seen in the main lair earlier - there was no immediate way to tell them apart or identify them, and he wasn't going to hang around long enough to study them for identifying marks. More concerning to the Doctor there were also several smaller creatures in there. They were miniature copies of the larger ones. Some were two thirds the size, some half the size and others smaller still. There was a fresh corpse in this new cave. He wasn't able to tell the colour of the t-shirt he was wearing using night vision, but he had a leg missing - it was the dying teenager he'd tried to comfort. There was no other bodies in there, just the one that the smaller creatures were all picking and feeding on. It was a crèche. The Doctor knocked a small soft piece of loose limestone down from where he was leaning to see into the cavern below him. It dropped down onto a ledge and he was startled by movement on there. He ducked back into the tunnel holding his breath. Nothing happened so he dared to return to see what it was. Laying on a ledge a metre and a half below him was another adult. Behind it was a clutch of large eggs. They were breeding. Successfully by the looks of it. This was a much bigger problem than the Doctor realised. Bigger than he had imagined. The nursery chamber had several different paths in and out of it and he couldn't blow all of those up, not with the explosives he had available to him in the TARDIS.
He backed up to scan with the sonic screwdriver. There were three close exits to the surface in addition to the vertical shaft he'd come down. It looked like the drains and caves spread out for miles through the limestone. There were narrow gullies and tunnels cut through by rain water over the centuries that had been connected and linked with larger ancient tunnels and brought to the surface by manmade tunnels and drains. If the whole area was infested then there could have been hundreds of the creatures down there, not just the eight he'd previously seen. It made no sense to him. Why hadn't they been seen? Why weren't there immediately dismissed drunken stories of giant lizard dogs or local legends of man-eating dinosaurs devouring people who entered into the woods? How could all of this gone unnoticed?
He needed a new plan. His plan to blow up the tunnels into the lair and their food supply wasn't only going to fail to solve the problem, if they were all using it as a food store then it would make things worse. He didn't have enough charges on the TARDIS to blow up nine tunnels and he didn't think he was going to be able to access them all without passing straight through occupied caverns. He needed to head back. He could do a full geological scan of the area with the TARDIS. He might be able to determine how many of them there were and how far they extended. Maybe he could coral them into a smaller area. Drive them back using sonic pulses until he could seal them in. He would see how plausible that would be, and, in the meantime he could set up sonic pulses on any entrances he found to keep them underground.
The Doctor got up from his perch. He was thinking about what he was going to do, trying to plan it out, and his foot skidded in the limestone slime. He didn't fall, but he did splashed the standing water. The adults in the chamber below snapped round looking up to the noise he'd made. Some of the youngsters down there adopted the same stance, while others snarled at him, pouncing at thin air as if they could reach him. The juveniles might not have been able to leap two metres up to his position - he wasn't sure if the same could be said of the adults.
Without taking his eyes off them he retreated away from the edge at the same time as he sought the nearest exit to the air with sonic. He got his bearings and bolted. He doubted he'd be able to outrun them, and as he glanced over his shoulder he skidded off his feet almost missing the adjacent tunnel and the closest escape to the surface. He leap back up and yelped as he almost bowled into the largest of the creatures he'd seen yet. The Doctor dived back down, rotating in the air, so he slid across the rocks face up and aiming to direct a sonic pulse. The creature howled back down into the caves. The Doctor's hearts were hammering in his chest. That one was big. It had been huge! That was not big dog big, that was enormous dog big, obese St Bernard big. The Doctor couldn't afford the time to catch his breath as he picked himself up. The exit to the surface was only a few metres to his right.
There was a shallow shelf just round the bend and when he looked at it, the walls were covered in deep gouges - horrific claw marks. Nestled on the shelf were more eggs. The shells were still soft, sticky, and wet. They'd only just been laid. Had he just disturbed a female laying her eggs? If there was a nursery area, why had eggs been laid in an vague nest that was little more than a clawed indentation in the rock? The Doctor didn't contemplate the questions for long. They knew he was in there and he needed to get out. He could figure it all out back at the TARDIS.
The Doctor had needed a sample to analyse in order to find out what they were and where they were. He took one of the eggs and then apologised as he used sonic to vibrate and break the remaining eggs within their shells. They would never hatch, but hopefully the mother would still guard them not realising they'd fail. The Doctor sighed. He didn't like killing anything, but he'd eat an egg at that stage for breakfast with no qualms. These alien monsters just a spot of cells on a yolk. He still felt saddened by what was happening - it wasn't their fault. He kept his stolen egg secure and ran - taking the nearest exit. It didn't bring him up into the woods and there was no metal grille blocking it or preventing movement in or out.
He had come out into a stinking shallow stream running along a wide concrete gulley with a tarmacked side leading up onto a carpark. There was a disused building of some kind with a high wire fence around it. Brambles guarded a broken pathway and buddleia clung to life on the derelict brickwork. Thinking back to the map of the area he'd seen, he thought he was on the grounds of an old estate.
There didn't appear to be anything following him out of the tunnel so he took a moment to breathe and rounded the side of the building. A crooked wooden sign hung right across a large broken gate into the area. The faded letters revealed the building's previous industry. It was a slaughterhouse. The estate used to have acres and acres of land with tenanted farms. They must have had their own slaughterhouse and butchery on the grounds. Had they been cutting corners with their waste management? Is that what had brought the creatures there?
There had been pigs, sheep, cows, and horses in the main larder. Had some madman been using the creatures to dispose of the carcasses? Had the abundance of food meant that their population had grown beyond the space they had and the meat provided? Is that why they were now taking people as well? There were so many questions that needed to be answered. It needed to be fully investigated. If anyone linked to the slaughterhouse knew where the creatures were from then maybe he could get them back to where they were supposed to be, but relocating a breeding population of viokent carnivores was going to be a lot harder than moving the eight he'd originally seen. He had to at least consider it, because, he feared the only alternative was going to be to kill them.