She thought how preposterous it was that she should be asking the question and said to herself: ‘If it wasn’t for Rory, he’d have slapped me back long ago.’

He said: ‘That would be routine procedure, wouldn’t it, Mrs Alleyn?’

‘You were alongside this cabin when you—when you—were in that boat. The porthole was open. I heard about the suitcase.’

He glanced with something like irritation at the porthole.

‘There’s nothing of the nature of the object you describe in the suitcase,’ he said and stood up with an air of finality. ‘I expect you’ll appreciate, Mrs Alleyn, that we’ll ask for signed statements from all the personnel in this craft.’

‘Yes, of course.’

‘I’ve suggested they assemble in the saloon upstairs for a preliminary interview. You’re feeling quite yourself again—?’

‘Quite, thank you.’

‘That’s fine. In about five minutes, then?’

‘Certainly.’

When he had gone, softly closing the door behind him, Troy tidied herself up. The face that looked out of her glass was pretty white and her hand was not perfectly steady but she was all right. She straightened the red blanket and turned to the washbasin. The tumbler had been half-filled with water and placed on the shelf. Beside it were two capsules.

Trankwitones, no doubt.

Persistent woman: Miss Hewson.

Never in her life, Troy thought, had she felt lonelier. Never had she wished more heartily for her husband’s return.

She believed she knew now for certain, what had happened to Hazel Rickerby-Carrick. She had been murdered and her murderer was aboard the Zodiac.

‘But,’ she thought, ‘it may stop there. She told Miss Hewson about the jewel and Miss Hewson may well have told—who? Her brother almost certainly and perhaps Mr Pollock with whom they seem to be pretty thick. Or the Tretheways? For the matter of that, every man and woman of us may know about the thing and the ones like Dr Natouche and Caley Bard and me may simply have used discretion and held their tongues.

‘And then it might follow that some single one of us,’ she thought, ‘tried to steal the jewel when she was asleep on deck and she woke and would have screamed and given him—or her—away and so she got her quietus. But after that—? Here’s a nightmarish sort of thing—after that how did poor Hazel get to Ramsdyke weir seven miles or more upstream?’

She remembered that Miss Rickerby-Carrick had been presented with some of Miss Hewson’s Trankwitones and that Dr Natouche had said they were unknown to him.

Now. Was there any reason to suppose that the case didn’t stop there but reached out all round itself like a spider to draw in Andropulos and behind Andropulos, the shadowy figure of Foljambe? The Jampot? The ultra-clever one?