“Aha,” he said. “I thought so. Look, Banks, do you see that damage there, to the frontal lobes?”

Banks saw it. And he knew what it meant. “Contre coup?”

“Exactly. Which might explain the unusual angle.”

If a blow is delivered while the victim’s head is stationary, then the damage is limited to the point of impact – bones splintered into the brain – but if the victim’s head is in motion, then the result is a contre coup injury: additional damage opposite the point of impact. Contre coup injuries are almost always the result of a fall.

“Luke fell?”

“Or he was pushed,” said Glendenning. “But as far as I can tell, there are no other injuries, no broken bones. And as I said, if there was bruising, if someone hit him, say, knocked him over, then, unless there are any small bones in the cheek broken, we won’t be able to tell. We’ll be checking, of course.”

“Can you give me any idea about time of death? It’s important.”

“Aye, well… I’ve looked over Dr. Burns’s measurements at the scene. Very meticulous. He’ll go far. Rigor’s been and gone, which indicates over two days at the temperatures noted.”

“What about the wrinkling and whitening?”

“Cutis anserina? Three to five hours. Water preserves, delays putrefaction, so it makes our job a little harder. There’s no lividity, and I’m afraid it’ll be almost impossible to tell whether there was any other bruising. The water takes care of that.” He paused and frowned. “But there’s the discoloration around the neck.”

“What about it?”

“That indicates the beginnings of putrefaction. In bodies found in water, it always starts at the root of the neck.”

“After how long?”

“That’s just it,” Dr. Glendenning said, looking at Banks. “You understand I can’t be more specific, I can’t give you less than a twelve-hour margin of error, but not until at least three or four days, not at the temperatures Dr. Burns recorded.”

Banks made a mental calculation. “Bloody hell,” he said. “Even at the outside, that means Luke had to have been killed just after he went missing.”

“Sometime that very night, by my calculations. Taking everything into account, between about eight P.M. and eight A.M.”

And Dr. Glendenning’s calculations, perhaps because of his insufferable habit of being unwilling to commit himself to a specific time, were usually not far from the truth. In which case, Banks thought, Luke had died before Annie had even paid her first visit to Swainsdale Hall, let alone before she had followed Martin Armitage to the site of the drop.

Before she went off duty – though such a thing was somewhat of an illusion in the thick of a major murder investigation – Annie had made a few inquiries around the bookshops, asking after the couple who had tried to sell Norman Wells books he believed were stolen, but she drew a blank. Before meeting Banks for a drink at the Queen’s Arms, she had also checked recent shoplifting reports but turned up nothing there, either. The artist’s impression would be in the evening paper, so she would see what happened after that. There was something else she had intended to do, but it was like that name you can’t quite remember, the one on the tip of your tongue. If she put it out of her mind, it would come to her eventually.

Banks was already waiting for her at a corner table, and she saw him before he saw her. He looked tired, Annie thought, and distracted, smoking and staring into the distance. She tapped him on the shoulder and asked him if he wanted a refill. He came back from a long way and shook his head. She bought herself a pint of Theakston’s bitter and walked over to join him. “So what was that mysterious message about your wanting to see me?” she asked.

“Nothing mysterious about it at all,” Banks said, brightening up a little. “I just wanted to deliver a message myself, in person.”

“I’m all ears.”

“It looks as if you’re off the hook as far as Luke Armitage’s death is concerned.”

Annie felt her eyes open wide. “I am? How?”

“Dr. Glendenning pegs time of death at least three or four days ago.”

“Before-”

“Yes. Before the kidnap call even came in.”

Annie raised her eyes to the ceiling and clapped her hands. “Yes!”

Banks smiled at her. “Thought you’d be pleased.”

“How? He didn’t drown, did he?”

Banks sipped some beer. “No,” he said. “Pending tox results, it looks as if cause of death was a blow to the cerebellum, quite possibly the result of a fall.”

“A struggle of some sort, then?”

“Exactly what I thought. Perhaps with the kidnapper, very early on. Or whoever he was with.”

“And that person decided to try and collect anyway?”

“Yes. But that’s pure speculation.”

“So Luke died somewhere else and was dumped in the tarn?”

“Yes. Probably wherever he was being held – if he was being held. Anyway, there’d have been a fair bit of blood, the doc says, so there’s every chance of our still finding evidence at the original scene.”

“If we can find the scene.”

“Exactly.”

“So we are making progress?”

“Slowly. What about the girl?”

“Nothing yet.” Annie told him about her meeting with Norman Wells.

She noticed Banks was watching her as she spoke. She could almost see his mind moving, making the connections, taking a shortcut here and filing this or that piece of information away for later. “Whoever they are,” he said when she’d finished, “if Wells is right and they had been shoplifting, then that tells us they’re short of money. Which gives them a motive for demanding a ransom if they were somehow responsible for Luke’s death.”

“More speculation?”

“Yes,” Banks admitted. “Let’s assume they got into a fight over something or other and Luke ended up dead. Maybe not intentionally, but dead is dead. They panicked, thought of a suitable spot and drove out and dumped him into Hallam Tarn later that night, under cover of darkness.”

“They’d need a motor, remember, which might be a bit of a problem if they were broke.”

“Maybe they ‘borrowed’ one?”

“We can check car-theft reports for the night in question. No matter how much they covered up the body, there might still be traces of Luke’s blood.”

“Good idea. Anyway, they know who Luke’s parents are, think they might be able to make a few bob out of them.”

“Which would explain the low demand.”

“Yes. They’re not pros. They’ve no idea how much to ask. And ten grand is a bloody fortune to them.”

“But they were watching Martin Armitage make the drop, and they saw me.”

“More than likely. Sorry, Annie. They might not be pros, but they’re not stupid. They knew the money was tainted then. They’d already dumped Luke’s body, remember, so they must have known it was just a matter of time before someone found it. They could expect the footpath restrictions to work in their favor for a while, but someone was bound to venture over Hallam Tarn eventually.”

Annie paused to digest what Banks had said. She had made a mistake, had scared the kidnappers off, but Luke had already been dead by then, so his death wasn’t down to her. What else could she have done, anyway? Stayed away from the shepherd’s shelter, perhaps. Red Ron was right about that. She had guessed that the briefcase contained money. Did she need to know exactly how much? So she had behaved impulsively, and not for the first time, but it was all salvageable – the case, her career, everything. It could all be redeemed. “Have you ever thought,” she said, “that they might have planned on kidnapping Luke right from the start? Maybe that was why they befriended him in the first place, and why they had to kill him. Because he knew who they were.”

“Yes,” said Banks. “But too many things about this seem hurried, spontaneous, ill-thought-out. No, Annie, I think they just took advantage of an existing situation.”