In one spot, a few yards from its termination, the ground was wet and boggy. Crossing this wet place there were again the marks of footsteps, and amongst them the shoes with rubber studs.

Poirot followed the path on a little way, the inspector by his side.

'You noticed the women's footprints?' he said suddenly.

The inspector laughed.

'Naturally. But several different women have walked this way - and men as well. It's a regular short cut to the house, you see. It would be impossible to sort out all the footsteps.

After all, it's the ones on the window-sill that are really important.' Poirot nodded.

'It's no good going farther,' said the inspector, as we came in view of the drive. 'It's all gravelled again here, and hard as it can be.' Again Poirot nodded, but his eyes were fixed on a small garden house - a kind of superior summer-house. It was a little to the left of the path ahead of us, and a gravelled walk ran up to it.

Poirot lingered about until the inspector had gone back towards the house. Then he looked at me.

'You must have indeed been sent from the good God to replace my friend Hastings,' he said, with a twinkle. 'I observe that you do not quit my side. How say you. Doctor Sheppard, shall we investigate that summer-house? It interests me.' He went up to the door and opened it. Inside, the place was almost dark. There were.one or two rustic seats, a croquet set, and some folded deck-chairs.

I was startled to observe my new friend. He had dropped to his hands and knees and was crawling about the floor.

Every now and then he shook his head as though not satisfied. Finally, he sat back on his heels.

'Nothing,' he murmured. 'Well, perhaps it was not to be expected. But it would have meant so much ' He broke off, stiffening all over. Then he stretched out his hand to one of the rustic chairs. He detached something from one side of it.

'What is it?' I cried. 'What have you found?' He smiled, unclosing his hand so that I should see what lay in the palm of it. A scrap of stiff white cambric.

I took it from him, looked at it curiously, and then handed it back.

'What do you make of it, eh, my friend?' he asked, eyeing me keenly.

'A scrap torn from a handkerchief,' I suggested, shrugging my shoulders.

He made another dart and picked up a small quill - a goose quill by the look of it.

'And that?' he cried triumphantly. 'What do you make of that?' I only stared.

He slipped the quill into his pocket, and looked again at the scrap of white stuff.

'A fragment of a handkerchief?' he mused. 'Perhaps you are right. But remember this - a good laundry does not starch a handkerchief.' He nodded at me triumphantly, then he put away the scrap carefully in his pocketbook.