He was wretchedly waiting where he had been told to wait: between the lock and the lockhouse. The fog down here was dense indeed and they were upon him almost before they saw him. He seemed to be standing to attention and expecting the worst.

‘Ever heard of a Misconduct Form?’ Tillottson ominously began.

‘Sir.’

‘Superintendent Alleyn’s got something to say to you.’

‘Sir.’

Alleyn said: ‘What happened, Cape?’

There had, he said, been a commotion on board the Zodiac. He couldn’t see anything much because of the Creeper but he heard the Skipper’s voice asking what was wrong and a woman taking on a fair treat, shrieking: ‘Let me go. Let me go.’ He went down to the moorings and called out: ‘What seems to be wrong there?’ but as far as he could make out the happening was on the far side. And then one of the gentlemen on board came round the deck and asked PC Cape where he was and said he’d better come on board and get things under control like. He could hardly see a thing except that there was a gap between the edge and the gunwale. He couldn’t see the gentleman either but said he had a very loud voice.

‘Go on.’

The loud voice said he could jump for it and as he could just make out enough for that he did jump and came aboard in a flounder and nearly lost his helmet. Alleyn gathered that a sort of blind search had set in under circumstances of the greatest possible confusion. Cape had proceeded with outstretched arms doing a breast stroke action, to the starboard side which was the farthest removed from the tow-path. He had bumped into a number of persons and had loudly demanded that everybody should keep calm.

A strange disordered mêlée now took place in the greatest possible confusion. Presently it occurred to Cape that the woman’s voice could no longer be heard. He had got alongside the Skipper and they had, between them, rounded up the passengers and herded them into the saloon where after a good deal of milling about and counting of heads, Miss Hewson’s head was found to be missing.

By this time the policemen on the pub side of The River had become alerted and started to cross the bridge.

Cape and the Skipper went through the cabins and searched the craft. All available lights were switched on but were not much help on deck where the fog was now of the pea-soup variety.