Banks and Annie left the abattoir as it was when they found it and walked back to the farmhouse. The front door was locked, but one of the officers soon got it open with his mini battering ram, the “red door knocker” as it was affectionately called. Nobody gave any thought to a warrant. A police officer’s life was in danger, and they had every reason to suspect the person who lived there of serious crimes.

The inside of the farmhouse was almost as unsavory as the abattoir. Cups, pans, plates, knives and forks stood piled in the stained sink, unwashed for days, or weeks. A plate on the small table with mold growing out of what had once been food on it, mouse droppings everywhere, signs of rats, too. On the wall was a rack of knives, and not Henckels cookware, either. These were nasty blades, clearly designed for the skinning and gutting of animals, or ­people. They were the only clean objects in the place, sharp blades so lovingly polished you could see your face in them.

Though Banks and Annie wore latex gloves, they were careful not to touch anything as they went methodically through the place, the bedroom, with its unruly mess of sheets, like the apparition from the adaptation of M. R. James’s “Oh, Whistle, and I’ll Come to You” Banks had seen on television at Christmas. The toilet was a pigsty, the rest of the upstairs drab, bare and dusty. And nowhere were there any signs of Winsome or Atherton.

Banks supposed that was a good thing. At least they hadn’t found her tied to a bed with a bolt pistol wound between her eyes. That meant there was a good chance she had escaped, or was at least on the run. If she had headed for the moors with Atherton in pursuit, Banks would put his money on Winsome. He had seen her in chases, and she was fast and strong. Whether either had the stamina to get very far under these conditions, however, remained doubtful.

It was down in the cellar where they found the hydroponic setup. Marijuana plants, lots of them, along with about a kilo of hash and a similar amount of cocaine, clearly from elsewhere. Drugs were another of Atherton’s little sidelines. He had no doubt supplied Caleb Ross with the wacky baccy he had smoked.

“We’ll seal the cellar off for now,” Banks said. “It’s more important to get search parties for Winsome organized. They can’t have got far. Have a word with the patrol officers. They might know the area a bit better than we do. I don’t suppose there’s any chance of getting a helicopter out in this weather, but it’s worth asking, too.”

Annie walked over to the nearest patrol car, leaning down to speak through the window. Banks looked around. The snow showed no signs of abating. He imagined Winsome caught in a drift, slowly freezing to death. He put away such disturbing thoughts when he heard a car approaching. It turned out to be a dark blue Focus, and it appeared around the bend in the drive and pulled to a halt behind the police four-­by-­four.

Though he had never met Terry Gilchrist before, Banks recognized him from the car he drove, his limp and Winsome’s description. “Oh, bloody hell,” he said as Gilchrist advanced through the snow. “What are you doing here?”

“I thought you might need some help.”

“It’s a police operation,” said Banks. “We don’t normally involve civilians, not even ex-­military.”

“So that’s all the thanks I get for fighting for my country? Not to mention driving all this way in a bloody Ford Focus?”

Banks shrugged.

“What exactly are you doing that you don’t want my help on?”

“Why don’t you just get back in your car and head for home, Mr. Gilchrist. Leave it to us.”

“It’s Winsome, isn’t it? I knew something was wrong when she didn’t call.”

“Yes, it’s Winsome,” said Banks, losing his temper. “She’s a friend and a colleague and I’d like you to clear out of here and let us do our job.”

Gilchrist stood his ground and looked around the farmyard. “It doesn’t look to me as if you’re actually doing very much.”

“That’s your opinion.”

Gilchrist sighed. “Look, Chief Inspector, you may not like me, or you may simply not like the idea of someone telling you your business, but if you’re looking for Winsome, I might be able to help. And if I think what’s happened is true, the sooner the better.”

Banks was suddenly interested. “Oh? And what do you think happened?”

“Do you know where you are?”

“High Point Farm. You said you’d never heard of it. I blame myself for letting it slip.”

“I hadn’t, but it was easy to look up. You’re within a quarter of a mile of Woadly Edge, though you can’t see it from here in this weather. It’s up that hill and across the moors a ­couple of hundred yards or so.”

“So?”

“Winsome and I have had a few conversations. I wouldn’t say I know her well, but I do know one or two things about her that I think you ought to consider.”

“Those being?”

“First off, Woadly Edge is one of the main access points for the Swainsdale cave system. And second, Winsome used to be a keen potholer. She’d know the caves like the back of her hand.”

“So you’re saying . . .”

“You’re catching on. If she was in trouble out here, the odds are she’d run for the caves. It would give her an advantage.”

“And her chances once she’d got there?”

“Depends on whether someone was after her, and whether that someone also knows the system. It’s not for novices, though, so he’d have to be an experienced potholer. The odds that he’s not are good. There aren’t that many.”

“From what I know of him, I doubt he goes potholing in his spare time. More like pulls the legs off flies. What would you advise us to do, assuming this is true?”

“Get up there right away and find out if I’m right.”

Banks said nothing.

As if sensing and understanding his indecision, Gilchrist said, “Look, I know you don’t want ­people like me interfering, but I assure you I also have experience of the caves. I have military training, too. I can handle myself, despite the injury.” He held his arms out. “Look, no stick.”

“You don’t need it?”

“Actually, it’s in the car, and I could certainly use it to get to Woadly Edge. But once I’m inside, no. As long as I don’t have to run.”

“This is against my better judgment,” said Banks.

“Come on, we should get going. Bring the others. We might need some help clearing the entrance.”

Banks spoke to Annie and two of the patrol officers while Gilchrist got his walking stick and torch, along with two spades they found in the yard, then the four of them set off up the rise toward Woadly Edge. It didn’t take long to get there, and the drifts had not covered the entrance. A gaping dark hole showed in stark contrast against the white surroundings. The snow was light enough that they could walk straight through it.

“That’s her jacket,” said Banks, pointing his torch toward the middle of three cave entrances. “That’s Winsome’s jacket.”

His voice echoed. They were standing in a sort of stone hallway or foyer with a high ceiling, or so it seemed to Banks, and Winsome’s quilted jacket lay on the ground in front of the central of three openings. There was no trace or sign of Atherton.

“That’s a dead end,” said Gilchrist. “She was trying to misdirect him.”

“Which means she knew he was after her, and he wasn’t far behind,” said Banks. “She must be bloody freezing.”

Gilchrist bent forward and went into the right-­hand tunnel.

“What are you doing?”

Gilchrist looked back. “If she went anywhere,” he said, “it was down here. She’d know as well as I do about the left-­hand entrance.”

“What about it?”

“It gets too narrow. This one’s narrow in parts, too, but it’s the only way in from here.”

“Into where?” Annie asked.

“I don’t have time to explain,” said Gilchrist, edging forward even as he spoke, “but it’s a large system of passages and caverns, one of the biggest in Europe. There are miles and miles of connected caves in there, but it’s a bit like a maze.”