“But that’s different from knowing your private address and so on,” Shelley objected. “After all, the letter was addressed to you personally at your home address. Don’t forget that.”

“I’m in the ’phone book,” Moss reminded him.

“Yes, that’s so,” said Shelley. He felt almost “stumped.” The thing did, on reflection, seem almost inexplicable, unless the man was someone who knew Moss well, he thought; and yet each of the little points, which in sum seemed to mean so much, had a perfectly natural explanation. But to the trained mind of the detective the explanations somehow did not quite ring true. There seemed to be something forced, something vaguely unnatural about them. He could not manage to lay his finger on any particular spot in the explanation which was wrong; and yet, taken as a whole it was all wrong. The detective of wide experience gets these occasional “hunches,” and it was one of Shelley’s deepest feelings that they rarely proved wrong. He felt perfectly sure that in this instance he was correct; and that the criminal, whoever he might eventually turn out to be, would be someone well known to Moss.

Before he had time to put this matter before Moss, however, Cunningham returned, his face one broad beaming smile.

“Hullo, Cunningham,” he said with a smile which answered that on Cunningham’s countenance. “You look as if you’d picked up a five-pound note. That must mean that you have some good news for us.”

“Indeed, it does, sir.”

“Well, don’t waste time, man. Tell us all about it. Fire ahead.”

“The finger-prints on the envelope were entirely Mr. Moss’s, and someone’s who we couldn’t identify,” said Cunningham.

“Right. I understand your meaning, even if your grammar isn’t all it might be,” smiled Shelley. “Probably the postman is the gentleman whom you couldn’t identify.”

“Yes, sir. That’s what we thought.”

“And the letter, man. Don’t keep us waiting.” Shelley was clearly on tenterhooks.

“The letter had a distinct thumb-print on the back,” said Cunningham with a smile, “which was identified in the department.”

“Who was it?”

“Wallace. J. K. Wallace,” returned Cunningham.

Shelley looked puzzled for a moment, and then his memory became its usual efficient self. “J. K. Wallace,” he said reflectively. “That was the man who did ten years for a cheque-book fraud, isn’t it?”

“Yes, sir,” said Cunningham. “That was before my time at the Yard, though.”

“He came out about ten years ago,” said Shelley.

“How old would he be?” asked Cunningham.

Again Shelley reflected for a moment, and then: “Oh, not much over forty,” he said. “He was a very young fellow, not much over twenty when he was convicted. Ten years in prison, ten years out. Yes, that would make him fortyish now.”