Elliot barks out a laugh, but the noise dies away again quickly, perhaps embarrassed to be there. “I said, theoretically.”

Doggett rolls his eyes. “When you’ve finished theorizing, do you think you might be able to give us something a little more accurate?”

“The rule of three,” Tyler says. Three minutes without air, three days without water, three weeks without food.

“Very good, Sergeant—in this case the problem for our friend here would have been water. But if we take into account the fact he’d be panicking, expending energy trying to get out, he’d be losing fluids faster than average. Then there’s the trauma to the head, blood loss.” He pauses and sucks air between his teeth like a dodgy mechanic. “I doubt he’d have lasted longer than a couple of days. Maybe less.”

Long enough, though. How long before a man would attempt to burrow his way out through a cinder-block wall using nothing but his fingernails?

Elliot coughs and hacks up some phlegm. Doggett catches his eye, and the man swallows it again. He goes on. “My guess is he was badly injured. Probably concussed. With a bit of luck the poor sod didn’t even know what was happening to him.” He doesn’t sound like he believes it. “Poor old Gerry, eh? Who’d have thought it?”

“All right, Doc, go do your stuff. I’ll catch up with you later.” Doggett is already turning away. He shouts over his shoulder, “Tyler,” as though calling a dog to heel.

They leave the SOCOs to their work and head back toward the cellar steps. “Right,” Doggett says, planting his hands on his hips. “Murder equals Murder Room. Last time I checked, you sit on the other side of the wall.”

Presumably that’s supposed to be a dig but he lets it go. He has his own rule: the first one you get free. “It’s an interesting case,” he says. “A cold case. I’m good at cold cases, DI Doggett. I can’t see why you’d turn down anyone’s help at this stage.”

Doggett grunts. “Depends who’s offering the help. All right, we’ll see what the DCI has to say, eh?” He starts back up the stairs.

Tyler takes a last look round the cellar. Something Doggett said about the builders when they came in raises a question in the back of his mind.

“Tyler!”

He turns and makes his way back up the cellar steps.

Outside, the sun sears Tyler’s eyes and burns away the damp from his skin.

Doggett leads him across the driveway, slowing as they pass the young officer who let Tyler through. “Constable Rabbani,” he calls.

“Sir.”

“I thought I said no one in without checking with me first?”

Rabbani glances at each of them in turn before lowering her head. “Yes, sir.”

“It wasn’t her fault. I pulled rank.”