The room had not been touched since the removal of Nathaniel’s body, and Joseph winced perceptibly at the sight of his dress-clothes, still laid out upon a chair. He turned away, shading his eyes with his hand, while the Inspector’s trained gaze absorbed every detail of the room.

The Inspector had studied the photographs taken of the corpse, but when Joseph seemed to have recovered a little from his emotion, he asked him to describe the position in which he had found his brother. He asked more questions, and Joseph soon warmed to his narrative, and might even, by unkind persons, have been thought to have been enjoying himself considerably. His own and Stephen’s shock lost nothing in the telling; he had a good memory, and was able with very little prompting to reconstruct the scene of the crime for Hemingway. He even presented him with two separate theories to account for the position in which Stephen’s cigarette-case had been found, which, as Hemingway afterwards remarked to his Sergeant, was excessive.

‘Nice old chap,’ said the Sergeant.

‘He’s nice enough, but he’ll very likely drive me mad before I’m through with this,’ returned Hemingway. ‘If I get a line on any of his blessed relatives, he’ll lie awake all night, thinking up a set of highly unconvincing reasons to account for their doings. Anything strike you about this case?’

The Sergeant stroked his chin. ‘I’d say it was a fair stinker,’ he volunteered.

‘Stinker!’ ejaculated Hemingway. ‘It couldn’t have happened!’

‘But it did happen,’ the Sergeant pointed out.

‘Yes, that’s what makes me wish I’d never joined the Force,’ said Hemingway. He walked into the bathroom, and gazed up at the ventilator. ‘If that was the only thing open, and they’re all agreed it was, it looks as though it has a very important bearing on the case. Hand me that stool, will you?’

The Sergeant brought the cork-topped stool to him, and he climbed onto it, to inspect the ventilator more closely.

‘If anyone got in that way, he’d have had to be a small man,’ said Ware. ‘The young fellow we saw downstairs couldn’t have done it.’

‘No one could have got in without scratching the paint with his shoes.’

‘Rubber soles,’ suggested the Sergeant.

‘You may be right. Assume someone did get in this way. How?’

‘I was thinking he might have climbed up by a ladder. There’s bound to be one in the gardener’s shed, for pruning the fruit trees.’

‘That doesn’t interest me. What I want to know is, how did he set about oozing through this highly improbable aperture once he had climbed up the ladder?’

The Sergeant considered the ventilator, and sighed. ‘I see what you mean, sir.’

‘Well, that’s something, anyway. Head first, that’s how he must have got in, and nothing to catch hold of inside. The inference is he squirmed in, dropped on to his head on the floor, picked himself up, not a penny the worse for wear, and walked in to murder the old man, who hadn’t heard a sound.’