"Hoop la!" replies Charlie in subdued staccato; "I'm takin' ye; commalong." Cautiously they wend their way down the dark, narrow street, into a filthy alley, and through it to an open space laid bare by some recent fire. Here they halt for a moment, Charlie peering curiously around him, and stooping to search for something among the loose stones. Suddenly a shriek pierces the silence about them--a woman's shriek, thrice repeated, its tones fraught with agony and terror! Silly Charlie lifts himself suddenly erect, and turns his face toward a dark building just across the open space. Then, as the third cry sounds upon the air, both men, as by one humane instinct, bound across the waste regardless of stones and bruises, Silly Charlie flying on before, as if acquainted with every inch of the ground, straight toward the dark and isolated building. CHAPTER XIV. A PRETTY PLOT. In order to comprehend the cause of the alarm which stimulated to sudden action both the wise man and the fool, Van Vernet and Silly Charlie, let us turn back a little and enter the dark house at the foot of the alley. It is an hour before midnight. The place is dark and silent; no light gleams through the tightly boarded windows, there is no sign of life about the dwelling. But within, as on a previous occasion, there is light, life, and a measure of activity. The light is furnished by a solitary tallow candle, and the life supplied by the same little old man who, on a former occasion, was thrown into a state of unreasonable terror at sight of a certain newspaper advertisement. It is the same room, its appointments unchanged; the same squalor and dirt, the same bottle upon the same shelf, the same heap of rags in the corner, the same fragments of iron and copper on the floor. The same deal table and scrap of carpet are there, but not arranged as on a former occasion, for now the table is pushed back against the wall, the piece of carpet is flung in a wrinkled heap away from the place which it covered, exposing to view a dark gap in the floor, with a dangling trap-door opening downward. Beside this opening squats the little old man, his eyes as ferret-like and restless as usual, but his features more complacent and less apprehensive than when last we saw him. By his side is the sputtering tallow candle, and in his hand a long hooked stick, with which he is lowering sundry bags and bundles down the trap, lifting the candle from time to time to peer into the opening, then resuming his work and muttering meanwhile.