“But number seven knows he gave you a sample of his handwriting! And if word gets around about a particularly good-looking graphological genius—”

“Hollis isn’t in CID. I only involved him because we’d already discussed you. I told everyone the samples were for my ten-year-old niece who’s obsessed with graphology.”

“Is she?”

“She’s three and I hope she stays well away from the subject. Look, I won’t involve you. I can’t: nobody else would listen to ‘A graphologist says so’. Don’t worry.”

“I wasn’t worried, until you turned up and terrified me,” Wildsmith pointed out. “Let me get this straight. You asked your colleagues to contribute simply to make up the numbers? You didn’t suspect this man?”

“No. Or... No.”

“Really? Because if your only reason to suspect him now is a ginger beer in a moth-eaten cardigan telling you he’s a murderer on the basis of his handwriting—”

“I wouldn’t put it like that.”

“But here you are, looking sick as a dog, and I very much doubt that’s simply faith in my powers. You think I’m right about number seven. You’ve got reason to think I’m right.”

Aaron’s head felt slightly fuzzy with the thrum of panic, the urgent desire to squash it all away. Don’t think about it, don’t look.

If he wasn’t going to look, he should have gone back to Lisson Grove. He was here because Wildsmith’s incisive gift had cut through to a truth, and he had to face that.

He took a deep breath. “If what you say is true, a number of other things make sense. It forms a picture. A damned ugly picture, but a coherent one.”

“Is this man, number seven, clever?”

“Yes.”

“Dangerous?”

“Perhaps,” Aaron said, and had to add, “Yes.”

“Hell and the devil,” Wildsmith said. “So what are you going to do?”

Aaron knocked back a mouthful of gin. It was neat, oily, harsh on his throat. He never drank neat gin. “I’m going to look into it. There’s nothing else to do, is there? I can’t ignore it. He’s in a position to do an astonishing amount of harm.”

“Not just a constable then?”

“Don’t ask any more. I mean that. I’ve said too much.”

“Which is not your besetting sin,” Wildsmith said. “You came here because you needed to talk to someone. If you want to keep doing that, you can.”

Aaron’s throat hurt, in the clenched way that suggested he was getting a cold, or going to cry, except he hadn’t cried in a long time. “I don’t think that’s a good idea. You’d be best off staying entirely out of this.”

“And what about you? Are you going to bring anyone else in? Tell anyone at work what’s happening?”