Fox turned away from the telephone.

‘They’ve got through the list of guests, sir. Very smart work. Five men on five telephones. None of the guests admit to having overheard Lord Robert, and none of the servants.’

‘That’s our line, then. Find the interloper. Somehow I thought it would come to that.’ Alleyn wandered about the room. ‘Davidson was right; it’s a pleasant room.’

‘The house belongs to an uncle of Lady Carrados, doesn’t it?’

‘Yes, General Marsdon. He would appear to be a fellow of taste. The Greuze is charming. And these enamels. Where’s the offensive Cellini conversion, I wonder.’ He bent over the pie-crust table. ‘Nothing like it here. That’s funny. Davidson said it was on this table, didn’t he? It’s neither here nor anywhere else in the room. Rum! Must have belonged to one of the guests. Nothing much in it. Still, we’d better check it. What a hellish bore! All through the guests again, unless we strike it lucky! François might have noticed it sometime when he was doing the ash-trays. Better ask him.’

He rang up François, who said he knew nothing of any stray cigarette-case. Alleyn sighed and took out his notes. Fox cruised solemnly about the top landing.

‘Hi!’ called Alleyn after ten minutes. ‘Hi! Fox!’

‘Hullo, sir?’

‘I’ve been trying to piece these people’s movements together. As far as I can see, it goes something like this. Now pay attention, because it’s very muddly and half the time I won’t know what I’m talking about. Some time during the supper interlude Lady Carrados left her bag in this room. François saw Dimitri collect it and go downstairs. Miss Troy, who was dancing with Bunchy, saw him return the bag to Lady Carrados in the ballroom. Miss Troy noticed it looked much emptier than before. We don’t know if there were any witnesses to the actual moment when she left the bag, but it doesn’t matter. Bunchy saw her receive it from Dimitri. At one o’clock he rang me up to say he had a strong line on the blackmailer and the crucial conversation took place. Now, according to François, there were four people who might have overheard this conversation. Withers, Donald Potter, Sir Herbert Carrados, and the colourless Miss Harris, who may or may not have been in the lavatory, but was certainly on this landing. Someone else may have come and gone while François was getting matches for the enraged Carrados. On François’s return he went into the telephone-room and found it empty. Sounds easier when you condense it. All right. Our job is to find out if anyone else could have come upstairs, listened to the telephone, and gone down again while François was in the servants’ quarters. Withers says he heard the telephone when he was in the other sitting-room. He also says Carrados was up here at that time so, liar though no doubt he is, it looks as if he spoke the truth about that. Come on, Fox, let’s prowl.’