They parted company and Douglas went to bed. But he was overstimulated and slept restlessly. At last, finding himself broad awake and obsessed with their experiment, he had decided to get up and look through the calculations they had been working on that evening. He had stretched out his hand to his bedside-table when he heard a sound in the passage beyond his door. It was no more than the impression of stealthy pressure, as though someone advanced with exaggerated caution and in slow motion. Douglas listened spellbound, his hand still outstretched. The steps paused outside his door. At that moment he made some involuntary movement of his hand and knocked his candlestick to the floor. The noise seemed to him to be shocking. It was followed by a series of creaks fading in a rapid diminuendo down the passage. He leapt out of bed and pulled open his door.

The passage was almost pitch dark. At the far end it met a shorter passage that ran across it like the head of a T. Here, there was a faint glow that faded while Douglas watched it, as if, he said, somebody with a torch was moving away to the left. The only inhabited room to the left was Markins’. The back stairs were to the right.

At this point in his narrative, Douglas tipped himself back on the sofa and glanced complacently about him. Why, he demanded, was Markins abroad in the passage at a quarter to three in the morning (Douglas had noted the time) unless it was upon some exceedingly dubious errand? And why did he pause outside his, Douglas’s door? There was one explanation which, in the light of subsequent events, could scarcely be refuted. Markins had intended to enter Douglas’s room and attempt to steal the keys of the workshop.

‘Well, well,’ said Fabian, ‘let’s have the subsequent events.’

They were, Alleyn thought, at least suggestive.

After the incident of the night Douglas took his keys to bed with him and lay fuming until daylight when he woke Fabian and told him of his suspicions. Fabian was sceptical. ‘A purely gastronomic episode, I bet you anything you like.’ But he agreed that they should be more careful with the keys and he himself contrived a heavy shutter which padlocked over the window when the room was not in use. ‘There was no satisfying Douglas,’ Fabian said plaintively. ‘He jeered at my lovely shutter, and didn’t believe I went to bed with the keys on a bootlace round my neck. I did, though.’