Poirot passed behind the latter to where a dark stain on the carpet showed just before the window. He remembered the millionaire saying, ‘At twenty-eight minutes past three I open the second drawer on the right of my desk, take out the revolver that I keep there, load it, and walk over to the window. And then—and then I shoot myself.’

He nodded slowly. Then he said:

‘The window was open like this?’

‘Yes. But nobody could have got in that way.’

Poirot put his head out. There was no sill or parapet and no pipes near. Not even a cat could have gained access that way. Opposite rose the blank wall of the factory, a dead wall with no windows in it.

Stillingfleet said, ‘Funny room for a rich man to choose as his own sanctum, with that outlook. It’s like looking out on to a prison wall.’

‘Yes,’ said Poirot. He drew his head in and stared at the expanse of solid brick. ‘I think,’ he said, ‘that that wall is important.’

Stillingfleet looked at him curiously. ‘You mean—psychologically?’

Poirot had moved to the desk. Idly, or so it seemed, he picked up a pair of what are usually called lazy-tongs. He pressed the handles; the tongs shot out to their full length. Delicately, Poirot picked up a burnt match stump with them from beside a chair some feet away and conveyed it carefully to the waste-paper basket.

‘When you’ve finished playing with those things . . .’ said Stillingfleet irritably.

Hercule Poirot murmured, ‘An ingenious invention,’ and replaced the tongs neatly on the writing-table. Then he asked:

‘Where were Mrs Farley and Miss Farley at the time of the—death?’

‘Mrs Farley was resting in her room on the floor above this. Miss Farley was painting in her studio at the top of the house.’

Hercule Poirot drummed idly with his fingers on the table for a minute or two. Then he said:

‘I should like to see Miss Farley. Do you think you could ask her to come here for a minute or two?’

‘If you like.’

Stillingfleet glanced at him curiously, then left the room. In another minute or two the door opened and Joanna Farley came in.

‘You do not mind, Mademoiselle, if I ask you a few questions?’

She returned his glance coolly. ‘Please ask anything you choose.’

‘Did you know that your father kept a revolver in his desk?’

‘No.’

‘Where were you and your mother—that is to say your stepmother—that is right?’

‘Yes, Louise is my father’s second wife. She is only eight years older than I am. You were about to say—?’

‘Where were you and she on Thursday of last week? That is to say, on Thursday night.’

She reflected for a minute or two. ‘Thursday? Let me see. Oh, yes, we had gone to the theatre. To see Little Dog Laughed.’

‘Your father did not suggest accompanying you?’

‘He never went out to theatres.’

‘What did he usually do in the evenings?’