Hemingway was unimpressed. ‘Nothing to stop him giving notice, if he couldn’t stand Mr Herriard,’ he said. ‘Unless, of course, he’d got a legacy coming to him?’

‘That I don’t know, not having seen the will, but I should not think he had. He’d only been with Mr Herriard a matter of a few months. Mind you, he never said Mr Herriard was a hard master! It was the butler told me that. Ford spoke very nicely about his master. Spoke up for Mr Stephen, too.’

‘What’s he like?’ demanded Hemingway.

‘Wiry little chap, about thirty-five or six, I’d say. Bit scared of me, he was, but he spoke out quite honest and aboveboard, and didn’t try to throw suspicion on to anyone – except Mr Roydon, maybe, though he was only telling me what it was his duty to, after all.’

‘What about the butler?’

‘I’d say he was all right. Very starchy he is, but not above putting his ear to keyholes. He doesn’t like Mr Stephen, but that’s nothing. He’s been some time with Mr Herriard.’

‘Might be coming in for a legacy, of course,’ said the Chief Constable. ‘He’d hardly commit a murder for it, though. Not a man like Sturry. Besides –’ He paused, frowning, and then said, shooting a look at Hemingway from under his brows: ‘Not the point. I told you this was the devil of a case, Inspector. The suspects aren’t worrying me: it’s how the deuce the murder was committed at all.’

‘What, you aren’t going to tell me this is one of these locked-door cases you read about, sir?’ exclaimed Hemingway incredulously.

‘It is, just that. Now, you listen to the facts as we know them! Roydon read his play to the rest of the house-party after tea yesterday. It ended in a general row; the party split up, and went off upstairs to change for dinner, leaving Miss Clare in the library, and Joseph Herriard trying to smooth his brother down in the drawing-room. Nat then went up to his room, still furious. Miss Clare, who came out of the library just as he was going upstairs, heard him slam his bedroom door. She and Joseph then went up together. They were the last people except the murderer, of course – to see Nat alive. Some time between then, which must have been between seven-thirty and eight, and when the party gathered in the drawing-room again for cocktails, Nat was stabbed to death in his bedroom. When he didn’t join the party, Joseph went up to tell him they were all waiting for him. He found Ford outside Nat’s door, pretty worried at getting no answer to his knocking. The door was locked, and when Ford and Stephen Herriard forced the lock, Nat was lying dead on the floor, with the windows latched securely, both the door into his bedroom and that from his bathroom on to the upper hall locked on the inside, and only the ventilator above the bathroom window open.’