“Cormoran,” said Robin, who was far less interested in either Izzy’s mood or Barclay’s whereabouts than in the theory Strike was withholding from her, “have you seriously got an idea that explains everything you just told me?”

“Yeah,” said Strike, scratching his chin, “I have. Trouble is, it brings us closer to who, but I’m still damned if I can see why they did it, unless it was done out of blind hatred—but this doesn’t feel like a red-blooded crime of passion, does it? This wasn’t a hammer round the head. This was a well-planned execution.”

“What happened to ‘means before motive’?”

“I’ve been concentrating on means. That’s how I got here.”

“You won’t even tell me ‘he’ or ‘she’?”

“No good mentor would deprive you of the satisfaction of working it out for yourself. Any biscuits left?”

“No.”

“Lucky I’ve still got this, then,” Strike said, producing a Twix from his pocket, unwrapping it and handing her half, which she took with a bad grace that amused him.

Neither spoke until they had finished eating. Then Strike said, far more soberly than hitherto:

“Tonight’s important. If there’s nothing buried in a pink blanket at the bottom of the dell, the whole Billy business is finished: he imagined the strangling, we’ve set his mind at rest and I get to try and prove my theory about Chiswell’s death, unencumbered by distractions, without worrying where a dead kid fits in and who killed her.”

“Or him,” Robin reminded Strike. “You said Billy wasn’t sure which it was.”

As she said it, her unruly imagination showed her a small skeleton wrapped in the rotten remains of a blanket. Would it be possible to tell whether the body had been male or female from what was left? Would there be a hair grip or a shoelace, buttons, a hank of long hair?

Let there be nothing, she thought. God, let there be nothing there.

But aloud, she asked:

“And if there is—something—someone—buried in the dell?”

“Then my theory’s wrong, because I can’t see how a child strangling in Oxfordshire fits with anything I’ve just mentioned.”

“It doesn’t have to,” said Robin reasonably. “You could be right about who killed Chiswell, and this could be an entirely separate—”

“No,” Strike said, shaking his head. “It’s too much of a coincidence. If there’s something buried in the dell, it connects to everything else. One brother witnessing a murder as a child, the other blackmailing a murdered man twenty years later, the kid being buried on Chiswell’s land… if there’s a child buried in the dell, it fits in somewhere. But I’ll lay odds there’s nothing there. If I seriously thought there was a body in the dell, I’d’ve tried to persuade the police to do the job. Tonight’s for Billy. I promised him.”

They sat watching the track fade gradually from sight in the darkness, Strike occasionally checking his mobile.

“Where’s bloody Barclay got—? Ah!”

Headlights had just swung onto the track behind them. Barclay advanced an old Golf up the track and braked, turning off his lights. In her wing mirror, Robin watched his silhouette leave the car, turning into the flesh and blood Barclay as he reached Strike’s window, carrying a kit bag just like the detective’s.

“Evenin’,” he said laconically. “Nice night for a grave robbin’.”

“You’re late,” said Strike.

“Aye, I know. Just got a call from Flick. Thought you’d want tae hear what she’s got tae say.”

“Get in the back,” Strike suggested. “You can tell us while we’re waiting. We’ll give it ten minutes, make sure it’s properly dark.”

Barclay clambered into the back of the Land Rover and closed the doors. Strike and Robin twisted around in their seats to talk to him.

“So, she calls me, greetin’—”

“English translation, please.”

“Cryin’, then—not to mention shittin’ herself. The police came calling today.”

“’Bout bloody time,” said Strike. “And?”

“They searched the bathroom and found Chiswell’s note. She’s been interviewed.”

“What was her explanation for having it?”

“Didnae confide in me. All she wanted was to know where Jimmy is. She’s in a right fuckin’ state. It was all ‘just tell Jimmy they’ve got it, he’ll know whut I mean.’”

“Where is Jimmy, d’you know?”

“Havenae a scooby. Saw him yesterday and he didnae mention any plans, but he told me he’d pissed off Flick by askin’ if she had Bobbi Cunliffe’s number. He took a liking to young Bobbi,” said Barclay, grinning at Robin. “Flick told him she didnae know and wanted to know why he was so interested. Jimmy said he was jus’ tryin’ to get Bobbi along to a Real Socialist meetin’, but, y’know, Flick’s not that fuckin’ dumb.”

“D’you think she realizes it was me who tipped off the police?” asked Robin.

“Not yet,” said Barclay. “She’s panickin’.”

“All right,” said Strike, squinting up at the little of the sky they could see through the foliage overhead, “I think we should get started. Grab that bag beside you, Barclay, I’ve got tools and gloves in there.”

“How’re ye gonnae dig wi’ your leg like that?” asked Barclay skeptically.

“You can’t do it on your own,” said Strike, “we’ll still be here tomorrow night.”

“I’m digging, too,” said Robin firmly. She felt braver after Strike’s assurances that they were highly unlikely to find anything in the dell. “Pass me those wellies, Sam.”

Strike was already extracting torch and walking stick from his kit bag.

“I’ll carry it,” offered Barclay, and there was a sound of heavy metal tools shifting as he hoisted Strike’s bag onto his shoulder along with his own.

The three of them set off along the track, Robin and Barclay matching their pace to Strike’s, who progressed carefully, focusing the beam of his torch on the ground and making regular use of the stick, both to lean on and push obstacles out of his way. Their footsteps were deadened by the soft ground, but the quiet night amplified the chink and clatter of the tools carried by Barclay, the rustling of tiny, unseen creatures fleeing the giants who had invaded their wilderness and, from the direction of Chiswell House, the barking of a dog. Robin remembered the Norfolk terrier, and hoped he wasn’t loose.

When they reached the clearing, Robin saw that night had turned the derelict cottage into a witch’s lair. It was easy to imagine figures lurking behind the cracked windows and, telling herself firmly that the situation was quite creepy enough without imagining fresh horrors, she turned away from it. With a soft “ooft,” Barclay let the kit bags fall onto the ground at the lip of the dell and unzipped both. By the light of the torch, Robin saw a wide array of tools: a pick, a mattock, two pinchbars, a fork, a small ax and three spades, one of them with a pointed head. There were also several pairs of thick gardening gloves.