Word is received by the government officers that Andre Cuneo, a notorious counterfeiter, having served sentence in Italy, has been liberated and is headed for America. John Henshaw, a Secret Service detective, is put on the case. The counterfeiter escapes arrest at the boat by getting over the side, where he is picked up by accomplices. Henshaw, missing him, is reprimanded by the office and the case is given to another man. Henshaw is heartbroken, but determines to take up the case on his own account. John Gordon, teller of a bank in the city, is a member of the gang, who is called by the name of "X-3" in their dealings, and it is through him that the counterfeit money is circulated. Gordon has a daughter, Ethel, who is in love with Frank Hilton, a moving picture actor. After a few months' time Gordon decides to abandon the gang and live straight for his daughter's sake. He notifies the gang of his intention and they swear to get even. A few nights later Gordon quarrels with Hilton about his daughter. They part in anger, the girl being a witness to part of their quarrel. Later that night Andre and Bryson come to Gordon's house. It is late and a bitter quarrel ensues between Bryson and Gordon, the former threatens exposure. Gordon loses his head and draws a gun and in the scuffle is killed. The murderers escape and the next day Hilton is accused of the crime and arrested. Henshaw reads the account, goes to the house and is begged by the daughter to clear Hilton. He agrees to do so. He obtains linger impressions of the murderers and later an impression of the fingerprints on one of the counterfeit bills. He shadows Bryson and through this locates the counterfeiters' den. Meanwhile the police have given up the search, as all evidence points to Hilton. Henshaw engages an apartment in the same building with Bryson, taps the telephone line and overhears a conversation between the counterfeiter and Bryson. He notifies the police and lays in wait outside their door. Bryson, coming to the den, finds him there. He gets the rest of the gang and they overpower Henshaw and take him to the basement. He is bound and fastened to a trap, which is to be sprung by a candle burning the rope in two. The counterfeiters pack up their belongings and attempt to leave. They are taken by the police before they can get away; they do not tell, however, about the capture of Henshaw. The trap is sprung but the rope breaks, throwing Henshaw into a sewer and from which he later escapes through underground sewers. Henshaw arrives at headquarters, proves that Bryson and Andre are guilty of Gordon's murder and Hilton is released. There is a happy reunion between Hilton and Ethel, who lays the consummation of their happiness to Henshaw.