More than once he had picked up some startling clews from anonymous letters, and he thought that perhaps “Sara P----” might know something of importance. Hester Street is not the finest street in Gotham. Neither is it a high-toned thoroughfare. There is a mixture of poverty and wealth on Hester Street, but society there in spots is not of the highest order. Carter entered the street with some misgivings, but not afraid. He walked leisurely up the street, looking for the number, and wondering what sort of looking woman his correspondent was. He found the house at last--a plain, two-story affair, with shutters in front and signs of age about the structure. No one appeared at the door to greet him, but he did not expect any one. He walked up the steps and turned the knob. The door opened easily, and he was in the hall. “The first door to the left,” he mentally said, and then he advanced toward it. In another second he had pushed this portal open and stood in a darkened room. He saw no one. Perhaps “Sara P----” was in another part of the house and had not heard him enter. Suddenly, however, he was undeceived, and in a flash he knew he had entered another trap. The floor gave way beneath his feet, as if his weight had suddenly broken it in. The entire floor seemed to fall. The detective made an effort to recover his equilibrium, but the Fates were against him. He fell down--down--and struck on his feet to pitch forward in Stygian darkness. At the same time a strange noise overhead told him that the floor had resumed its original position, and then for a few moments all was still. The trapped detective had to smile to himself in spite of his surroundings. He could not help laughing at his situation, however dark and hopeless it seemed to be; he had been cleverly caught, and the bait had secured the prize. It did not take him long to recover from the fall, which had not injured him; only jarred him up a little. He went forward and found a wall ahead. He followed the wall around, and came back to the same spot, as he could tell by a little stone under his feet. The dungeon apparently had no outlet; it was like a sealed-up prison of the olden time. Carter put up his hands, but could not touch the floor overhead. Of course he could not tell how far he had fallen, but he knew that the trap was directly above him. Had “Sara P----” sprung the trap? Had she lured him to this place to destroy him, and thus get even for some of his detective work? He did not doubt it. Nick Carter, in the underground prison, said nothing while he went around the walls. He heard no noises in the house overhead, and no one seemed to walk the floors there. At last the detective struck a match on the stone wall. It revealed the dimensions of the dungeon, and he surveyed it with eager curiosity. It was a dungeon sure enough. He saw the stone walls and the manner in which the stones were put together. There was no escape.