Their mission is perfectly obvious. Under ordinary circumstances, it was safe enough for the detective and his assistants to disguise themselves at home, and to return to their headquarters at their pleasure. When they were handling an unusually delicate case, however, or dealing with exceptionally clever lawbreakers, they found it necessary to take further precautions, and these so-called halfway houses then came in handy. In other words, the secret bases of supplies—each of which had two exits—made it possible for them to leave and return to their headquarters openly, and without disguise, although the intervening hours might be devoted to the most relentless shadowing, carried on under all sorts of guises. The man who climbed the stairs at the One Hundred and Twenty-fifth Street place, therefore, might easily have been Nick in the act of returning from some such expedition. He did not look in the least like the great detective, but that proved nothing, and his actions went far to indicate that he was Nick or one of the latter’s assistants. He boldly approached the door of the room, the location of which did not seem to give him the slightest trouble, despite the fact that there was nothing on the door to guide him. He seemed to have some little difficulty in getting the door open, to be sure; but, after working at the lock for two or three minutes, he gained entrance. Many criminals would have given a great deal to know the location of one of those rooms, but Nick did not dream that one rascal had long since discovered the halfway house in Harlem. The man who had gained entrance by picking the lock was Green-eye Gordon, of course. He had learned of the place shortly before Nick had caught him, two years or more back, and had been more or less uncertain as to the present use of the room. The detective might have given it up in the interval, for all he knew, but he had resolved to put his knowledge to the test, and now he was rewarded, for a glance about the place showed him that it was still employed by the detective. Rows of clothing hung in orderly array on hooks along the walls. At one side there was a long mirror, which enabled one to view oneself from head to feet, and between the windows, at the rear, was a dressing table, which looked as if it might belong to some musical-comedy star, so cluttered was it with make-up materials of all sorts. It was nearly an hour later when Ernest Gordon let himself out, locked the door behind him—after some further effort—and sauntered downstairs. Another complete transformation had taken place in his appearance. He was no longer the hunted criminal who had escaped from Clinton Prison, no longer the dressy individual who had presented himself at the detective’s, the day before, and least of all did he look like the man who had ascended those stairs some fifty minutes previously. Now, to all intents and purposes, he was Nick Carter himself.