Alleyn paused.

‘I’m afraid this is heavy going,’ he said. ‘I won’t be much longer. Watchman, when hit, pulled out the dart and threw it into the floor. When Oates called for the dart Legge obligingly found it on the floor behind the table but not before Oates, who’s a sharp fellow, Nick, had, as he says, spotted it a-lying there. You throw these darts down as often as you like and I’ll guarantee they stick in. And moreover we’ve statements from them all that it did stick in. All right. The lights had been wavering on and off throughout the evening. Before Watchman died they went off. There was a horrid interval during which Watchman made ghastly noises, everybody tramped about on broken glass, and Cubitt felt somebody’s head butt against his legs. Miss Moore, she told me, heard somebody click the light to see if it would go on. Not very bright of Miss Moore. Legge clicked the light to make sure it would stay off. He then dived down to find the telltale iodine bottle and plant the innocent one under the bench. He must, as you say, have found the bottom of the bottle hard to smash and have thrown it in the fire. You remember he called out that he would throw wood on the fire in order to get a little light. Just as he did that the lights went on. There’s a second switch in the inglenook, you know. He’d done another job of work in the dark. He’d picked up the dart and infected it with cyanide. The dart was sticking in the floor, well away from the others. He had only to feel for the table and then find the dart. Here he made the fatal mistake of adding a fancy-touch. We’ve proved that the dart was infected after the accident. Legge’s fingerprints are all over it. If anyone else had pulled it out of the floor they would either have left prints of their own or smudged his. He should have left the dart alone, and we would have concluded that if it was ever poisoned the stuff was washed off by blood or had evaporated.’

‘I cannot conceive,’ said the colonel, ‘why he’d wanted to anoint the dart. Why implicate himself? Why?’

‘In order that we should think exactly what we did think. “Why,” we cried, “there was Legge, finding the dart, with every opportunity to wipe it clean and he didn’t! It couldn’t be Legge!” Legge’s plan, you see, depended on the theory of accident. He made it clear that he could have done nothing to the dart beforehand.’

‘Then,’ said the colonel, ‘if the rest of this tarradiddle, forgive me, my dear fellow, is still in the air, we yet catch him on the point of the dart.’