My idea was to go at once to the Magnificent, and relate to Miss Marvell what had occurred, but Poirot vetoed the plan, and insisted that the morning would be time enough. I gave in rather grudgingly.

In the morning Poirot seemed strangely disinclined to stir out. I began to suspect that, having made a mistake to start with, he was singularly loath to proceed with the case. In answer to my persuasions, he pointed out, with admirable common sense, that as the details of the affair at Yardly Chase were already in the morning papers the Rolfs would know quite as much as we could tell them. I gave way unwillingly.

Events proved my forebodings to be justified. About two o'clock, the telephone rang. Poirot answered it. He listened for some moments, then with a brief "Bien, j'y serai" he rang off, and turned to me.

"What do you think, mon ami?" He looked half ashamed, half excited. "The diamond of Miss Marvell, it has been stolen."

"What?" I cried, springing up. "And what about the 'full of the moon' now?" Poirot hung his head.

"When did this happen?"

"This morning, I understand."

I shook my head sadly. "If only you had listened to me. You see I was right."

"It appears so, mon ami," said Poirot cautiously. "Appearances are deceptive, they say, but it certainly appears so."

As we hurried in a taxi to the Magnificent, I puzzled out the true inwardness of the scheme.

"That 'full of the moon' idea was clever. The whole point of it was to get us to concentrate on the Friday, and so be off our guard beforehand. It is a pity you did not realize that."

"Ma foi!" said Poirot airily, his nonchalance quite restored after its brief eclipse. "One cannot think of everything!"

I felt sorry for him. He did so hate failure of any kind.

"Cheer up," I said consolingly. "Better luck next time." At the Magnificent, we were ushered at once into the manager's office. Gregory Rolf was there with two men from Scotland Yard. A pale-faced clerk sat opposite them.

Rolf nodded as we entered.

"We're getting to the bottom of it," he said. "But it's almost unbelievable. How the guy had the nerve I can't think."

A very few minutes sufficed to give us the facts. Mr Rolf had gone out of the hotel at 11:15. At 11:30, a gentleman, so like him in appearance as to pass muster, entered the hotel and demanded the jewel-case from the safe deposit. He duly signed the receipt, remarking carelessly as he did so:

"Looks a bit different from my ordinary one, but I hurt my hand getting out of the taxi." The clerk merely smiled and remarked that he saw very little difference. Rolf laughed and said: "Well, don't run me in as a crook this time, anyway. I've been getting threatening letters from a Chinaman, and the worst of it is I look rather like a Chink myself - it's something about the eyes."