The look which accompanied these words told him that they were meant for a terrible threat, and the tightly shut hands of the speaker were proof that she was a fitting sister for Claude Lamont. “We will meet again, perhaps,” said the detective. “I am going to run the guilty down. That is my present mission.” At this moment Perry Lamont raised his head and looked at the detective. “I’m not to be trifled with,” said he. “I can make it hot for the man who brings us down to Mother Flintstone’s level.” “Well, you may proceed to do your worst,” was the cool answer. “You may be ‘disgraced,’ as you say, by the relationship, but this affair must not stop there.” With this parting shot the detective put out his hand to open the door, but the white fingers of the daughter closed about his wrist. “Beware,” she almost hissed. “I don’t know who took the old hag’s life, but you must not connect her with our family.” The detective shook the grip off and looked again at Perry Lamont. His head had dropped upon his breast, and his face was deathly white. “He’s gone into one of his strange spells,” said the girl. “You see that he is almost an imbecile. At times he seems his old self, but in reality he is but a human wreck. I’ll give you ten thousand dollars to quit this ‘trail,’ as you call it.” Ten thousand dollars! Nick was silent and the girl took it as a sign of hesitation. “I’ll write out the check now,” she went on. “It shall be paid any way you want it.” The detective shook his head. “You won’t, eh?” cried Miss Lamont. “I’m simply Nick Carter, and he has never been in the market, miss,” was the response. In an instant the girl’s countenance changed again from expectancy to wrath. She opened the door and pointed into the hall. “Take what comes!” she hissed, and with this Carter walked out. CHAPTER XXI. THE CARD CLEW. Jack Redmond’s death promised to give the police of New York another job, but no one suspected that he was Carter’s spy. The woman who had seen the strange man go up to Redmond’s room had given her information to the detective alone, and Nick kept it to himself. He did not doubt that the crook had been put out of the way because he was on the right trail in the matter of spying, and as he--Carter--had set Jack to keep track of Claude Lamont, he resolved to turn his own attention to that young man. Then, the disappearance of Margie from the Trocadero, whither she had gone to meet a person discovered to be the millionaire’s son, was an additional incentive for the detective, and he went from Lamont’s mansion to a certain part of the city where he expected to find the heir. Through it all he did not lose sight of the fact that he was Mother Flintstone’s avenger. That he kept in mind all the time, and with all his foresight he went back to the original trail.