He descended the stairs and rejoined Musgrave, who was standing in a dark place on the opposite side of the street. "Have you seen a light in that window?" asked Nick, pointing to the flat. "No." "Then Jones lied to me a minute ago when he said that his wife had just gone to bed. That window is in the principal bedroom of the flat." "There's been no light there." "Then they've fooled you, Musgrave." "What do you mean?" "I mean that Mrs. Jones is out." "It can't be possible." "It's true. She's gone out disguised as her own servant." "I can't believe it. Why, the girl's black as your hat." "That's why they engaged her, in my opinion. It made the trick easier. A black face is a good disguise. But I'm going to be sure about it." "How?" "I'm going to see whether the colored girl is in the flat." "How can you get in?" "I'm going down the air shaft. The servant's room opens on that shaft. They'll have made her go in there so that her light won't show, as it would if she were in the kitchen." Nick went to an engine-house near by, where he secured a coil of knotted rope. He wished to make his investigations secretly, so as not to put Jones on his guard. It would not have been safe to get into the flat by the ordinary methods. By using the fire escape of the building next door to the flat house, Nick got to the roof. The top of the air shaft was covered with a framework, in which large panes of glass were set. Nick removed one of them. Then he made his rope fast, and crept through the space where the glass had been. The Jones' flat was next to the top, so Nick had a short descent. But there was an awful stretch of empty air under him as he hung there. The shaft went to the basement floor, about seventy feet below the level of the window which opened into the room occupied by the Jones' new servant. He found that window readily. One glance through it was enough to satisfy him. There sat the colored girl, reading a book. Nick's suspicions had been correct. Naturally he did not delay very long in the air shaft. He had a hard climb to make, hand over hand, to the roof. The instant that his eyes rested on the girl, he began the ascent. He had gone up less than six feet when the rope suddenly gave way, and he found himself plunging downward through the shaft. CHAPTER VII. THE WARDROBE OF GASPARD'S FRIEND. Nick Carter is hard to kill. A good many crooks have tried to put him out of the world, and a fair percentage of them have lost their own lives in the attempt without inflicting any injury upon Nick. He is a man of resources, and that's what saves him. When one thing fails him, he finds something else to take its place. And so, when that rope gave way, he took the next best thing. That happened to be the sill of the window of Mr. Jones' bath-room. Nick seized it with a grip of iron as he shot downward. The strain on his arms was something awful, but he held on. His fingers gripped the wood till they dented it.