It was their boast that they never kept records of any sort.”

Dessert was brought, and after this interruption, Sir Frederic continued.

“One foggy January night sixteen years ago, a caretaker entered Mr. Hilary Galt’s private office, presumably deserted for the day. The gas lights were ablaze, the windows shut and locked; there was no sign of any disturbance. But on the floor lay Hilary Galt, with a bullet in his brain.

“There was just one clue, and over that we puzzled for many weary months at the Yard. Hilary Galt was a meticulous dresser, his attire was perfect, always. It was perfect on this occasion - with one striking exception. His highly polished boots - I presume you call them shoes over here - were removed and standing on a pile of papers on top of his desk. And on his feet he wore a pair of velvet slippers, embellished with a curious design.

“These, of course, seemed to the Yard the essential clue, and we set to work. We traced those slippers to the Chinese Legation in Portland Place. Mr. Galt had been of some trifling service to the Chinese minister, and early on the day of his murder the slippers had arrived as a gift from that gentleman. Galt had shown them to his office staff, and they were last seen wrapped loosely in their covering near his hat and stick. That was as far as we got.

“For sixteen years I have puzzled over those slippers. Why did Mr. Hilary Galt remove his boots, don the slippers, and prepare himself as though for some extraordinary adventure? I don’t know to this day. The slippers still haunt me. When I resigned from the Yard, I rescued them from the Black Museum and took them with me as a souvenir of my first case - an unhappy souvenir of failure. I should like to show them to you, Miss Morrow.”

“Thrilling,” said the girl.

“Annoying,” corrected Sir Frederic grimly.

Bill Rankin looked at Charlie Chan. “What’s your reaction to that case, Sergeant?” he inquired.

Chan’s eyes narrowed in thought. “Humbly begging pardon to inquire,” he said, “have you the custom, Sir Frederic, to put yourself in place of murderer?”

“It’s a good idea,” the Englishman answered, “if you can do it. You mean -“

“A man who has killed - a very clever man - he knows that Scotland Yard has fiercely fixed idea about essential clue. His wits accompany him. He furnishes gladly one essential clue which has no meaning and leads no place at all.”

Sir Frederic regarded him keenly. “Excellent,” he remarked. “And it has one great virtue - from your point of view. It completely exonerates your countrymen at the Chinese Legation.”

“It might do more than that,” suggested Barry Kirk.

Sir Frederic thoughtfully ate his dessert. No one spoke for some moments. But Bill Rankin was eager for more material.

“A very interesting case, Sir Frederic,” he remarked. “You must have a lot like it up your sleeve. Murders that ended more successfully for Scotland Yard -“

“Hundreds,” nodded the detective.