He crossed the shop noiselessly, cautiously, and passed through the door at the rear.

It opened into a short passage that, after a few feet, gave on a sort of corridor at right angles--and down this latter, facing him, at the end, the door of a lighted room was open, and he could see the figure of the man who had entered the shop, back turned, standing on the threshold.
Voices, indistinct, came to him.
The corridor itself was dark; and Jimmie Dale, satisfied that he was fairly safe from observation, stole softly forward.

He passed two doors on his left--and the curious arrangement of the building that had puzzled him for a moment became clear.

The store made the front of an old tenement building, with apartments above, and the rear of the store was a sort of apartment, too--the old lady's living quarters.
Step by step, testing each one against a possible creaking of the floor, Jimmie Dale moved forward, keeping close up against one wall.

The man passed on into the room--and now Jimmie Dale could distinguish every word that was being spoken; and, crouched up, in the dark corridor, in the angle of the wall and the door jamb itself, could see plainly enough into the room beyond.