‘I still have hopes. As it stands, there’s not a case in Thomas’s story to hang a dead dog on. They lose a tin of rat poison and find it in a garret. Somebody reads a book about embalming, and thinks up an elaborate theme based on an arbitrary supposition. Counsel could play skittles with it—as it stands.’

‘Suppose we did get an order for exhumation. Suppose they found arsenic in the body. With this embalming business it’d seem as if it would prove nothing.’

‘On the contrary,’ said Alleyn, ‘I rather think, Fox, that if they did find arsenic in the body it would prove everything.’

Fox turned slowly and looked at him. ‘I don’t get that one, Mr Alleyn,’ he said.

‘I’m not at all sure that I’m right. We’ll have to look it up. Here we are. I’ll explain on the way down to this accursed village. Come on.’

He saw his Assistant Commissioner, who, with the air of a connoisseur, discussed the propriety of an investigator handling a case in which his wife might be called as a witness. ‘Of course, my dear Rory, if by any chance the thing should come into court and your wife be subpoenaed, we would have to reconsider our position. We’ve no precedent, so far as I know. But for the time being I imagine it’s more reasonable for you to discuss it with her than for anybody else to do so—Fox, for instance. Now, you go down to this place, talk to the indigenous GP and come back and tell us what you think about it. Tiresome, if it comes to anything. Good luck.’

As they left, Alleyn took from his desk the second volume of a work on medical jurisprudence. It dealt principally with poisons. In the train he commended certain passages to Fox’s notice. He watched his old friend put on his spectacles, raise his eyebrows, and develop the slightly catarrhal breathing that invariably accompanied his reading.

‘Yes,’ said Fox, removing his spectacles as the train drew into Ancreton Halt, ‘that’s different, of course.’

Doctor Herbert Withers was a short, tolerably plump man, with little of the air of wellbeing normally associated with plumpness. He came out into his hall as they arrived, admitting from some inner room the sound of a racing broadcast. After a glance at Alleyn’s professional card he took them to his consulting-room, and sat at his desk with a movement whose briskness seemed to overlie a controlled fatigue.

‘What’s the trouble?’ he asked.

It was the conventional opening. Alleyn thought it had slipped involuntarily from Dr Withers’s lips.

‘We hope there’s no trouble,’ he said. ‘Would you mind if I asked you to clear up a few points about Sir Henry Ancred’s death?’

The mechanical attentiveness of Dr Withers’s glance sharpened. He made an abrupt movement and looked from Alleyn to Fox.