Noted detective Jarvis and his men are called one night to the scene of a murder in the tenderloin district. They find the bodies of two dead men on the floor of the café and a crazed gun-wielding tough at the door. Jarvis discovers on the floor a diamond earring and a woman's footprint. He takes the murderer to jail and after questioning him, during which process he remains dazed and silent, the police and detectives agree that the man is playing "possum" with them and they decide to lay a trap to catch him. The police let the murderer loose and secretly watch him. Out in the street he looks around, then with the same dazed look on his face he returns to jail and they lock him up, convinced that he is insane. But Jarvis maintains that he is either an idiot or a master mind. Another trap is set. The men at work in the jail yard are marching in file. Before the crook enters the jail doorway back to his cell, the floor closes and he sees that he is free, not knowing that eyes are secretly watching him. He escapes. The detectives follow him till he disappears over the wall of an estate owned by Dr, Baxter. The search reveals no one and upon returning to his office Jarvis originates a plan to trap the man. Baxter admits his guilt upon being caught, and as the detective is about to take him from the house, Mrs. Baxter pleads for a chance to say something. Jarvis listens to her. She tells a story of a foolish adventure with a young man. It is an auto ride, taken against Baxter's wishes. A breakdown follows and the nearest place of refuge is at a roadhouse. Here they enter and have dinner. While looking at the bill of fare, Mrs. Baxter sees that the roadhouse is one of the most notorious in the country. Her horror is increased when she is accosted by one of her husband's business associates, a worthless society scamp. Hastily she and her companion leave the place, but scandal has started. She returns home late that night and upon her arrival home in answer to her husband's anxious questioning, tells the first lie of her married life, saying: "I was with a woman friend." As time passes the society scamp comes and demands money in payment for his silence. She gives him what she has, and one day a note comes for more. The husband accidentally comes across the note and follows the directions thereof as to the meeting place. That night he follows his wife to the tenderloin district where the note demanded she come and pay the blackmail money. He is carefully disguised as a slum character and enters the café. He sees the money paid to the scamp by his wife, then the rascal notes the diamond earrings in the lady's ears and tears them from her. Unable to control himself, Baxter defends his wife and a battle follows in which the scamp and another man are shot. Thus was the crook arrested as he stood at the door. Jarvis, the detective, listens to the end of the story and then, rising, says: "I will give you five minutes to say good-bye to your wife; I'll be waiting on the porch." The parting is a sad one, and when Baxter comes to the porch it is empty. He is surprised. He goes to the detective's office and Jarvis sits at his desk, busy. Baxter says: "I have come to give myself up." Jarvis looks up crossly and answers: "Get out of here; visitors are not allowed in this office." After Baxter goes, Jarvis picks up the document of the Baxter case that reads "Unsolved cases."