‘Right,’ Alleyn got up, walked to the far end of the table and picked up the crumpled paper that still lay where Richard had thrown it down. ‘I must ask Colonel Warrender and Mr Dakers to give me a word or two in private. Perhaps we may use the study.’

They both rose with the same abrupt movement and followed him from the room, stiffly erect.

He ushered them into the study and turned to Fox who had come into the hall.

‘I’d better take this one solus, I think, Fox. Will you get the exhibits sent at once for analysis. Say it’s first priority and we’re looking for a trace of Slaypest in the scent spray. They needn’t expect to find more than a trace, I fancy. I want the result as soon as possible. Then go back to the party in there. See you later.’

In Charles Templeton’s study, incongruously friendly and comfortable, Warrender and Richard Dakers faced Alleyn, still not looking at each other.

Alleyn said: ‘I’ve asked you in here, without witnesses, to confirm or deny the conclusion I have drawn from the case-history, as far as it goes. Which is not by any means all the way. If I’m wrong, one or both of you can have a shot at knocking me down or hitting me across the face or performing any other of the conventional gestures. But I don’t advise you to try.’

They stared at him apparently in horrified astonishment.

‘Well,’ he said, ‘here goes. My idea, such as it is, is based on this business of the letter, which, since you seem to accept my pot shot at it, runs like this.’

He smoothed out the crumpled sheet of paper. ‘It’s pieced together, by the way,’ he said, ‘from the impression left on the blotting-paper.’ He looked at Richard. ‘The original was written, I believe, by you to Mrs Templeton when you returned, finally, to the house. I’m going to read this transcription aloud. If it’s wrong anywhere, I hope you’ll correct me.’

Warrender said: ‘There’s no need.’

‘Perhaps not. Would you prefer to show me the original?’

With an air of diffidence that sat very ill on him, Warrender appealed to Richard. ‘Whatever you say,’ he muttered.

Richard said: ‘Very well! Go on. Go on. Show him’

Warrender put his hand inside his coat and drew out an envelope. He dropped it on Charles Templeton’s desk, crossed to the fireplace and stood there with his back turned to them.

Alleyn picked up the envelope. The word ‘Mary’ was written on it in green ink. He took out the enclosure and laid his transcription beside it on the desk. As he read it through to himself the room seemed monstrously quiet. The fire settled in the grate. A car or two drove past and the clock in the hall told the half-hour.