‘He didn’t,’ said Alleyn. ‘Believe me, he didn’t. He’s a clumsy man. He fumbles. His hands are coarse and his fingers are thick. To get cyanide on that dart with seven pairs of eyes watching him, he’d need the skill and the hands of a conjurer. Even Abel Pomeroy, who thinks or wants to think Legge did the job, can’t offer an idea of how he did it. Parish who has thrown Legge in my teeth every time I’ve seen him, hasn’t an argument to offer. And on the other side we’ve got Will, Miss Moore, Miss Darragh and Cubitt all ready to swear with, I believe, perfect truth, that Legge, as he stood there under the light, had no chance of anointing the fourth or any other dart.’

‘But we can’t explain the poison in any other way.’

‘Oh, yes,’ said Alleyn, ‘I think we can. This is our case—’

IV

Five o’clock had struck and they were still at the police station. Alleyn had gone over every word of his report with Harper. He had described each interview and had sorted the scraps of evidence into two groups, the relevant and the irrelevant. He had poured prussic acid solution into Abel’s little jar and, to reproduce rat-hole conditions, had placed it in a closed drawer. At the end of forty-six minutes half had evaporated.

‘So you see,’ said Alleyn, ‘if the liquid you found in the tin is water, as I believe it is, it looks as if the murderer must have visited the garage within forty-six minutes. Now on that night—the night on which Watchman chipped Legge and Will Pomeroy lost his temper—Legge gave an exhibition of dart-throwing which lasted only a few seconds. This took place a few minutes after Abel had set the poison in the garage. The argument followed. Legge went into the public bar where he brought off the trick with the darts. He then returned and joined the others in a game of Round-the-Clock—’

‘There you are,’ interrupted Harper. ‘He could—sorry. Go on.’

‘I know he could, Nick, but wait a bit. According to your report they all, with the exception of Miss Darragh, who had gone to bed, stayed in the private taproom until closing time. Our forty-five minutes have gone.’

‘I suppose,’ said Harper, ‘one of them might have gone out for a few minutes without being noticed.’

‘Yes, and that is a point that will be urged by counsel. All we can prove here is opportunity—possibility. We can’t bring anything home. May we have the stuff you took from the rat-hole, Nick? Fox, would you get my bag? Mr Noggins was generous with his prussic acid and there are at least three ounces of the water, if it is water. The analyst can lend us half. Let’s poach on his preserves and find out for ourselves.’