‘For the love of heaven!’ Alleyn cried, ‘let us admit coincidence without further parley. It’s staring us in the face. It’s a bloody quaint coincidence that my wife should have been staying in this wretched dump, and there’s an end of it.’

He glanced at Fox’s respectable, grave, and attentive face. ‘I’m sorry,’ he said. ‘It’s no good expecting me to be reasonable over this business. Troy’s had one bad enough experience of the nastiest end of our job. She’ll never altogether forget it, and—well, there you are. One doesn’t welcome anything like a reminder.’

‘I’m sure it’s very upsetting, Mr Alleyn. If I could have—’

‘I know, I know.’ And looking at Fox, Alleyn felt a spasm of self-distaste.

‘Fox,’ he said suddenly, ‘I’m up against a silly complexity in my own attitude to my job. I’ve tried to shut it off from my private life. I’ve adopted what I suppose the Russians would call an unrealistic approach: Troy in one compartment, the detection of crime in another. And now, by way of dotting me one on the wind, the fates have handed Troy this little affair on a platter. If there’s anything in it she’ll be a witness.’

‘There may not be anything in it, Mr Alleyn.’

‘True enough. That’s precisely the remark I’ve been making to her for the last hour or so.’

Fox opened his eyes very wide. ‘Oh, yes,’ said Alleyn, ‘she’s already thought there was something off-colour about the festivities at Ancreton.’

‘Is that so?’ Fox said slowly. ‘Is that the case?’

‘It is indeed. She’s left us alone to talk it over. I can give you the story when you want it and so can she. But I’d better have your end first. What’s that paper you’ve got there?’

Fox handed it to him. ‘It came in to us yesterday, went through the usual channels, and finally the Chief got on to it and sent for me this evening. You’d gone by then, sir, but he asked me to have a word with you about it. White envelope to match, addressed in block capitals “CID, Scotland Yard, London.” Postmark, Victoria.’

Alleyn took the paper. It appeared to be a sheet from a block of faintly ruled notepaper. The lines were, unusually, a pale yellow, and a margin was ruled down the side. The message it contained was flatly explicit:

THE WRITER HAS REASON TO BELIEVE THAT SIR HENRY ANCRED’S DEATH WAS BROUGHT ABOUT BY THE PERSON WHO HAS RECEIVED THE MOST BENEFIT FROM IT.