'And the marble limb? That was last seen by you when?'

'Didn't I tell you, Chief Inspector? By me at about eleven thirty last night when I went to check the tide timetable. I was interested to estimate how long the launches would take on Saturday afternoon and returning to Speymouth that night. The water can run strongly between here and the mainland. Munter saw it in place just after midnight. I found that it was missing and the lock forced when I went to the kitchen at six fifty-five this morning.'

'And all the members of the house party had seen it and knew where it was kept.'

'All except Simon Lessing. He was swimming when the rest of the party were shown round the castle. As far as I know, he has never been near the business room.'

Grogan said:

'What is the boy doing here anyway? Shouldn't he be at school? I take it that Miss Lisle – Lady Ralston – was buying him a privileged education, that he isn't a day boy at the local comprehensive.'

The question could have sounded offensive, thought Buckley, if the carefully controlled voice had held a trace of emotion. Gorringe replied, equally calmly.

'He's at Melhurst. Miss Lisle wrote for special weekend leave. She may have thought that Webster would be educational. Unfortunately, the weekend has proved educational for the boy in ways she could hardly have foreseen.'

'A proper little mother to him was she?'

'Hardly that. Miss Lisle's maternal sense was, I should have thought, undeveloped. But she genuinely cared for the boy within her capacity. What you must understand about the victim in this case was that she enjoyed being kind, as indeed most of us do provided it doesn't cost us too much.'

'And how much did Mr Lessing cost her?'

'His school fees primarily. About £4,000 a year I suppose. She could afford it. It all began I imagine because she had a conscience about breaking up his parents' marriage. If she did, it was quite unnecessary. The man had a choice presumably.'

'Simon Lessing must have resented the marriage, on his mother's account if not his own. Unless, of course, he thought a rich step-mama a good exchange.'

'It was six years ago. He was barely eleven when his father walked out on him. And if you're suggesting, without much subtlety I may say, that he resented it enough to bash in step-mama's face, then he waited long enough to do it and he chose a singularly inappropriate time. Does Sir George Ralston know that you suspect Simon? He probably considers himself as the boy's stepfather. He'll want to take steps to see that the boy's interests are safeguarded if you're going on with that somewhat ridiculous idea.'

'I never said that we suspected him. And, in view of the boy's youth, I have agreed with Sir George that he shall be present when I speak to the boy. But Mr Lessing is seventeen. He's no longer a juvenile in law. I find these concerted measures to protect him interesting.'

'As long as you don't find them sinister. He was extremely shocked when I broke the news to him. His own parents are dead. He was devoted to Clarissa. It's natural that we should wish to minimize his pain. After all, you're hardly here in the capacity of child-care officers.'

Grogan had scarcely glanced at his witness during this exchange. The unlined notepad which he preferred to the normal police issue was on the desk blotter in front of him and he was sketching with his fountain pen. A careful oblong shape with two doors and two windows took shape under the huge speckled hand. Buckley saw that it was a representation of Clarissa Lisle's bedroom, something between a plan and a drawing… The proportions of the room were carefully to scale but small objects were being inserted, over-large and carefully detailed as a child might draw them; the jars of cosmetics, a box of cotton-wool balls, the tea-tray, the alarm clock. Suddenly and still without looking up, he asked:

'What made you go to her room, sir?'

'Just after Miss Gray went to call her? Merely a chivalrous impulse. I thought that, as her host, it would be seemly if I escorted her to her dressing-room. And there were things to be carried. Her make-up case for one. As we haven't much dressing-room accommodation and she was having to share with Miss Collingwood who plays Cariola, Miss Collingwood had undertaken to be dressed and out before the star wanted the room, but Miss Lisle wasn't going to risk anyone borrowing her greasepaint. So I went to carry the box and to escort the lady.'

'In the absence of her husband who would normally perform that service.'

'Sir George had just come in to change. We met at the top of the stairs as I've already explained.'

'You seem to have taken a lot of trouble for Miss Lisle.' He paused and added, 'One way or another.'

'Walking her two hundred yards from her room to the theatre hardly counts as trouble.'

'But putting on the play for her, restoring the theatre, entertaining her guests. It must have been an expensive business.'

'I'm not a poor man, happily. And I thought that you were here to investigate a murder not to inquire into my personal finances. The theatre, incidentally, was restored for my satisfaction not Miss Lisle's.'

'She wasn't hoping that you might partly finance her next professional appearance? What's the theatrical jargon, be her angel?'

'I'm afraid you've been gossiping to the wrong people. That particular angelic role has never attracted me. There are more amusing ways of losing money. But if you're trying tactfully to suggest that I may have owed Miss Lisle a favour, you're perfectly right. It was she who gave me the idea for Autopsy, my bestseller, in case you're one of the half-dozen who haven't heard of it.'

'She didn't write it for you, by any chance?'

'No, she didn't write it. Miss Lisle's talents were varied and egregious but they didn't extend to the written word. The book was fabricated rather than written, by an unholy triumvirate of my publisher, my agent and myself. It was then suitably packaged, promoted and marketed. No doubt there are sins to be laid to Clarissa's charge but Autopsy isn't one of them.'

Grogan let his pen drop from his hand. He leaned back in his chair and looked Gorringe full in the face. He said quietly:

'You knew Miss Lisle from childhood. For the last six months or so you've been intimately concerned with this play. She came here as your guest. She was killed under your roof. However she died, and we shan't know until after the post-mortem, the killer almost certainly used your marble to bash in her face. Are you sure that there is nothing you know, nothing you suspect, nothing she ever said to you that can throw any light on how she died?'

Put it any plainer, thought Buckley, and you'd have to be administering an official caution. He half expected Gorringe to reply that he would say nothing until he had seen his lawyer. But he spoke with the calm unconcern of a disinterested party who has been asked for his considered opinion and has no objection to giving it.

'My first thought – and it remains my theory – was that a trespasser had somehow gained access to the island knowing that my staff and I would be busy with preparations for the play and that the castle would be, as it were, undefended. He climbed up the fire escape, perhaps out of mischief or devilment and with no clear idea of what he meant to do. It could have been a young man.'

'The young usually hunt in gangs.'

'Several young men, then. Or a couple if you prefer it. One of them gets in with the general idea of a prowl round while the house is quiet That supposes a local boy, one who knew about the play. He creeps into Miss Lisle's room – she had forgotten to lock the communicating door or had thought the precaution unnecessary – and sees her apparently asleep on the bed. He is about to make his exit, with or without the jewel case, when she takes the pads off her eyes and sees him. In a panic he kills her, seizes the box and makes his escape the same way as he came in.'