“I’ll dig deep,” promised Roger. “Where’s the Rolls now, sir?”

“At the Clapham Police Station,” Turnbull answered.

“Wonder if it’s been run over for prints. I ought to have checked while I was there,” Roger said, aloud. “The constable who found Halliwell said that he thought the car stopped, didn’t he?”

“Yes,” Turnbull said.

“So Halliwell might have been in the car, and if he had, his fingerprints might be on it.” Roger shook his head. “That would be too good to be true. Any special instructions, sir?”

“Yes,” said Chatworth. “Prove the manslaughter case, whatever you do. Don’t let Raeburn get away with this.”

“Not if I can help it,” Roger said, fervently.

He left the AG’s office with Turnbull, spent ten minutes checking what had been done, then went down to his car again, and drove to Clapham. And still only Raeburn was on his mind, for Raeburn was not just another suspect: Raeburn was an obsession, a man with a great capacity for evil.

Arkwright, the constable who had found Halliwell, stood in front of Roger at the Clapham Police Station, holding his helmet in his hands. He was young and intelligent-looking, although obviously nervous.

“What made you think the Rolls Royce stopped?” asked Roger.

Arkwright was safe with that question. “Well, sir, first time I saw the car the headlights were on. I’d just turned on to the Common. The road’s a bit twisty, and my lamp wasn’t working properly, some dynamo trouble. I couldn’t see much, because of the trees and bushes, but I noticed that the headlamps went out, although I could see the rear light. I said to myself the driver was in trouble, and I was going to see if I could lend a hand when my lamp went right out, so I had to get off and get it working again. If only I’d known—”