She said in a shaken tone: ‘He went upstairs. Rather slowly. He held on to the banister-rail all the way. I thought he was putting over one of his crippled acts. I heard him slam his door when he got upstairs, and I – I laughed. You see, I thought –’

‘That doesn’t matter,’ Stephen interrupted. ‘What did Joe do? Did he know you were watching?’

She turned her head. ‘No. Not till I laughed.’

‘And then? What did he say?’

‘I don’t remember. Nothing in particular, I think. He gave a little start, but that was quite natural. Oh yes, and he did say that Nat had knocked the steps over on purpose! Then he carried the steps away to the billiard-room. I collected my handbag from this room, and put out my cigarette, and went up to change. Joseph overtook me at the top of the stairs. But – but it isn’t possible! It couldn’t have happened then!’

Stephen said: ‘Is it possible, Inspector? Was he stabbed then?’

‘You’ve got no right to ask me that, sir, and you know it. What’s more, I’ll have to warn you both –’

‘– to keep our mouths shut! You needn’t trouble!’

‘But the knife!’ Mathilda said. ‘I never saw it! What could he have done with that?’

‘Easy enough to have concealed it from you!’ Stephen said. ‘Up his sleeve, or even flat against the inside of his arm, with the hilt held downwards in the palm of his hand. You’d never see it!’ He turned to the Inspector. ‘Would it have been possible for my uncle to have walked upstairs after having been stabbed?’

‘A doctor could answer that better than I can, sir.’

‘Nevertheless, that is what you suspect. What put you on to it?’

‘When I’ve proved it to my satisfaction, sir, maybe I’ll tell you. Until then, I’m asking you and Miss Clare to behave as though we hadn’t had this highly illuminating interview.’

‘You needn’t worry!’ Stephen said, his eyes glittering. ‘Not for worlds would I do anything to impede the course of justice! Not – for – worlds!’

‘I think,’ said Mathilda, rather shakily, ‘that I’ll retire to my room with a headache. I don’t feel like meeting Joseph, and I certainly couldn’t act a part. I feel slightly sick.’

‘That’s right, miss, you go upstairs,’ said Hemingway. ‘It’s the best thing you could do.’

She moved to the door. Stephen opened it for her, and as she stepped into the hall, she gave an uncontrollable start, for Joseph was there.

‘Ah, there you are, Tilda!’ Joseph said. ‘I was just coming to look for you! Tea-time, my dear! Hallo, Stephen, old boy! Now, what mischief have you two been hatching, I should like to know?’

‘Mathilda’s got a bit of a head; she’s going to lie down,’ Stephen said, closing the door behind him. ‘Did you say tea was ready?’

‘Oh, poor Tilda!’ Joseph exclaimed, concerned. ‘Can I get you anything for it, my dear? Would you like an aspirin? I’m sure Maud has some.’