The spectacle of Filbon's anguish was not a pleasant one, and Nick moved a few paces away. But he kept his eyes on Filbon, who, rocking his body and sobbing violently, seemed to be in the lowest depths of despair. Suddenly, with a wild laugh, he straightened up. "I have settled it," he almost shouted. "It's all right now." Nick rushed forward, seized him by the arm, and let the lantern's light fall full upon his face. What he saw filled him with dismay. "What have you done?" he demanded harshly. "Got the stuff at a drug-store coming down here," was the answer, given with chattering teeth. "Fooled you, didn't I? Ha! ha!"--the laugh quickly ceased, the face grew ashen, the form stiffened, there was a sharp rattle in the throat, and Nick, dropping his bull's-eye, caught the body as it was falling forward. Luke Filbon, weak instrument of a woman's wicked cupidity, was dead. A small phial on the ground by the side of the body told the story of the fatal agency. It had contained prussic acid, one of the deadliest and quickest-acting poisons known to the pharmacopœia. It had been procured that evening at a Broadway drug-store, for the label was there, and there were the death's head and cross-bones below the word "Poison." By what representations had he obtained the poison? A visit to the drug-store would furnish the explanation. The detective was about to leave the spot, when a sudden thought caused him to stay his steps. In Filbon's pocket was the list of bank-notes which he had stolen and replaced. The peculiar happenings of the night contained mysterious suggestions. The list, apparently without value, might become useful. No harm in obtaining possession of it. It was found and placed in Nick's pocketbook. Now the detective hurried away to find a patrolman, state what had been discovered, and have the nearest police-station notified. When this duty had been performed, Nick went to the drug-store where the prussic acid had been purchased. He had left the phial where he had found it, for it bore evidence that would, at the coroner's inquest, in connection with an analysis of the contents of the dead man's stomach, absolutely determine the cause of death. It was an all-night drug-store, and the one clerk readily gave the information desired. He had known Filbon as a customer for many years, and the poison had been sold upon the representation that it was to be used for the asthma, with which Filbon's mother was afflicted. "Diluted with water, it is often used by asthmatics," said the clerk, "as it gives quick relief." When informed that the poison had been used for quite a different purpose, the clerk was horrified.