“Stop a moment!” Nick interposed. “What is wanted, Joseph?”

The office door had been opened by Nick’s manservant, who then paused respectfully on the threshold.

“Detective Vallon is here, sir,” he replied. “He wants to see Inspector Mallory.”

“Vallon here!” exclaimed Mallory surprisedly. “Let him come in, Nick. I’ll see what he wants.”

“Show him in, Joseph,” Nick directed.

He entered a moment later, a plain-clothes man, from police headquarters, with whom both Nick and Chick shook hands cordially, while he was briefly stating his mission.

“I’ve got a special delivery for you, inspector,” said he. “It is marked private and rush, and I reckoned it might be very important. The lieutenant said I’d be likely to find you here, so here I am—and here’s the letter.”

Inspector Mallory took it and glanced at the superscription. It was addressed with a lead pencil, in a somewhat coarse, irregular hand, which, with the misspelling of several words, plainly evinced the writer’s lack of education. Prominent in the lower corners of the envelope were the two words—rush and private.

“Humph!” Mallory grunted, with a puzzled expression. “Mailed this morning in Harlem. I don’t know the hand. Never saw one quite so scrawly. It may be important, nevertheless, Vallon, as you say.”

Chief Mallory broke the seal while speaking, then drew out the inclosed sheet of paper.