‘How dare you’ – Moppett began – ‘how dare you –’ and Leonard came into the room.

When he saw Mr Cartell he fetched up short. ‘Pardon me,’ he said elegantly. ‘Am I interrupting something?’

Moppett extended her arm towards him. ‘Darling,’ she said. ‘I’m being badgered. Can you cope?’

He took her hand and sat on the arm of her chair. ‘What goes on?’ he asked. He was normally a white-faced young man: this characteristic at the moment was particularly noticeable.

‘To be perfectly honest,’ Moppett began, ‘I haven’t a clue. But it appears that we’re meant to know where poor old P.P. puts his museum pieces.’

‘Mr Period’s cigarette-case has disappeared,’ Mr Cartell said, addressing Leonard exclusively. ‘You and Miss Ralston were the last persons known to handle it. You may care to make a statement as to what you did with it.’

Leonard said: ‘Disappeared! By Jove, that’s too bad, isn’t it?’ His pale fingers closed tightly over Moppett’s. ‘Of course, we must help if we can. Yes, now – yes. I do remember. I left it on the window-ledge in the dining-room. You remember, sweetie, don’t you?’

‘Perfectly.’

‘Was the window open or shut?’

‘Oh,’ Leonard said easily, ‘open. Yes. Open.’

‘Did you open it, Mr Leiss?’

‘Me? What would I do that for? It was open.’

‘It was shut,’ Mr Cartell said, ‘during luncheon.’

‘Then I suppose the butler-chap – what’s-’is-name – must have opened it.’

‘No.’

‘That,’ Leonard remarked, smiling, ‘is what he says.’

‘It is what I say.’

‘Then I’m afraid I don’t much fancy the way you say it.’ Leonard produced a silver case from his pocket, offered it to Moppett, helped himself and with great deliberation, lit both cigarettes. He snapped the case shut, smiled at Mr Cartell and returned it to his pocket. He inhaled deeply, breathed out the vapour and fanned it with his hand. He wore an emerald ring on his little finger. ‘How about the sewer in the lane?’ he asked. ‘Anything in that?’

‘They could not open the window from outside.’

‘Perhaps it was opened for them.’

Mr Cartell stood up. ‘Mr Leiss,’ he said, ‘I consider myself responsible to Mr Period for any visitors who, however unwelcome, come to his house under my aegis. Unless his case is returned within the next twelve hours, I shall call in the police.’

‘You’re quite an expert at that, aren’t you?’ Leonard remarked. He looked at the tip of his cigarette. ‘One other thing,’ he said. ‘I resent the way you’re handling this, Mr Cartell, and I know exactly what I can do about it.’

Mr Cartell observed him with a sort of astonished disgust. He addressed himself to Moppett. ‘There’s no point,’ he said, ‘in pursuing this conversation.’