There is a well-known French restaurant in the "Tenderloin" district which provides its patrons with small but elegantly appointed private dining-rooms.
The restaurant occupies a corner house; and, though its reputation is not strictly first-class in some respects, its cook is an artist, and its wine cellar as good as the best.
It has two entrances, and the one on the side street is not well lighted at night.
At half-past seven o'clock one evening Nick Carter was standing about fifty yards from this side door.
The detective had shadowed a man to a house on the side street, and was waiting for him to come out.
The case was a robbery of no great importance, but Nick had taken it to oblige a personal friend, who wished to have the business managed quietly. This affair would not be worth mentioning, except that it led Nick to one of the most peculiar and interesting criminal puzzles that he had ever come across in all his varied experience.
While Nick waited for his man he saw a closed carriage stop before the side door of the restaurant.
Almost immediately a waiter, bare-headed and wearing his white apron, came hurriedly out of the side door and got into the carriage, which instantly moved away at a rapid rate.
This incident struck Nick as being very peculiar. The waiter had acted like a man who was running away.
As he crossed the sidewalk he glanced hastily from side to side, as if afraid of being seen, and perhaps stopped.
It looked as if the waiter might have robbed one of the restaurant's patrons, or possibly its proprietor. If Nick had had no business on his hands he would have followed that carriage.
As it happened, however, the man for whom the detective was watching appeared at that moment.
Nick was obliged to follow him, but he knew that he would not have to go far, for Chick was waiting on Sixth avenue, and it was in that direction that the thief turned.
So it happened that within ten minutes Nick was able to turn this case over to his famous assistant, and return to clear up the mystery of the queer incident which he had chanced to observe.
Nick would not have been surprised to find the restaurant in an uproar, but it was as quiet as usual. He entered by the side door, ascended a flight of stairs, and came to a sort of office with a desk and a register.
It was the custom of the place that guests should put down their names as in a hotel before being assigned to a private dining-room.
