“It’s possible that the writer’s guilt or fear might shriek off the page. But it’s also possible that I’d simply get a strong sense of a personality. Suppose one hand strikes me as cruel and violent, and another as sly and vicious. I take a punt and say it’s the violent man, and you laugh at me because the case is a blackmail one. Meanwhile, my pick is beating his wife nightly.”

Aaron hadn’t thought of that. “Ah. Well, I suppose you’ll need to write down all your conclusions—have them written,” he added, as Wildsmith lofted his hook, “and give your probabilities.”

“But not half a dozen, or you’ll accuse me of hedging my bets, so I hope most of your suspects are reputable people. What if the real culprit isn’t in your pool of suspects at all?”

“Then the test won’t be valid. I’m not trying to trick you, Mr. Wildsmith. I just want to find out if you can do what you claim in conditions that make trickery impossible.”

“I’m sure. I have to say, my experience suggests that if you decide to believe me, you’ll see proof where it doesn’t exist, and if you’re determined not to, no proof will ever be enough.”

“I’m a Detective Sergeant of CID. I’m reasonably good at assessing these matters.”

“Hmph. And what happens as a result of this test?”

“In what sense?”

“Well, if I get it wrong, do you prosecute me for fraud? If I get it right, do you engage to defend me in the event of legal action?”

“Neither of those. Shall we say, we’re making a bet?”

“We could,” Wildsmith said. “What are the stakes?”

Aaron hadn’t thought that far. “If you get it right, I agree you can do what you claim.”

“And winning you round should be high enough stakes for me?” It sounded challenging, but there was a slight grin lurking, and he cocked his head as he spoke.

“I’d have thought winning would be its own reward,” Aaron said. “But I could throw in dinner.”

Wildsmith froze. Aaron had just a second to wonder why the devil he’d said that, then the graphologist’s mouth curved. “All right, but somewhere decent. None of your greasy spoons.”

“Perish the thought.” That wouldn’t have sounded flirtatious if he’d said it to a fellow officer, therefore it hadn’t sounded that way now. Aaron could feel the skin heating on his cheeks. He prayed it was the warm room.

“Dinner, then,” Wildsmith said. “And if I were to lose? I’m not growing a moustache again, before you ask.”

“I wouldn’t want you to. If you lose, I have my scepticism confirmed. That will do for me.”

Wildsmith gave him a squint-eyed look. “And this is not in any way official?”