A crooked detective masterminds a robbery then fights to keep his money.

Police detective Barney Nolan accosts a bookmaker, takes him into an alley and shoots him. Barney then robs the body of $25,000, removes the silencer from his gun, shouts a warning and fires two shots into the air to make it appear that he has shot a fleeing suspect. Barney is unaware the entire episode has been witnessed by a man in an adjacent building. When Sgt. Mark Brewster, the officer assigned to investigate the incident, asks Barney, who was his mentor, why he killed the man Barney answers that it was an accident. Capt. Gunnarson, the new precinct commander, concerned that Barney had previously been involved in two other killings, warns him to use better judgment. Barney then goes to meet his girl friend, Patty Winters, at the nightclub where she works. Becoming enraged when he sees the revealing costume she is wearing for her new job as a cigarette girl, Barney hits the club's owner and then leaves with Patty. Meanwhile, two private detectives, Fat Michaels and Laddie O'Neil, in the employ of gangster Packy Reed, visit Mark and tell him that the bookmaker was carrying $25,000 of Reed's money when he was killed. When Mark says that the police found only around $300 on the body, Michaels and O'Neil remind him that Barney was at the crime scene before he was. Cabot, a crime reporter with a low opinion of Barney, agrees not to write about the situation until Mark can investigate. After Barney tells Patty that his financial situation is improving, he takes her to see a model furnished house in a new estate. While Patty looks over the house, Barney quickly hides the cash in the backyard. Later, Mark tells Patty about Barney's situation and confides that he is concerned about Barney's hardened behavior. The next day, as an assistant district attorney begins to interview Barney, Ernst Sternmueller, the deaf-mute who witnessed the killing, comes to the office and hands the district attorney a note indicating he saw the entire incident. The district attorney shows the note to Barney, whom Ernst fails to recognize. After reading the message, Barney hands the mute a written reply stating that someone will come to interview him later. That night, as Ernst completes a written account of the incident, admitting that he could not see the killer's face, he receives a visit from Barney. When Barney looks out the window to the alley, turning his back to Ernst, Ernst recognizes Barney as the killer. When Barney tries to offer Ernst a bribe, he becomes frustrated because Ernst cannot hear him, and pushes him away. Losing his balance, Ernst falls against the bed frame and is fatally injured. Barney then tries to make Ernst's death look like an accident by pushing his body down a flight of stairs. Later, Barney summons Michaels and O'Neil to a bar, then beats them brutally with his revolver in front of horrified customers. Meanwhile, Mark investigates Ernst's death and discovers his written statement. When Barney returns home, he finds Mark waiting to arrest him for the bookmaker's murder. After Barney implicates himself in Ernst's death, Mark draws his gun, but Barney knocks it out of his hand and considers killing Mark, but cannot bring himself to do it. Instead, he knocks Mark out and leaves. Barney then goes to Patty's, awakens her and tells her they are leaving immediately. Patty, who suspects that the money Barney mentioned actually belongs to Reed, begs him to stay and let Mark help him straighten things out. Angered that Patty has been talking with Mark, Barney slaps her, then shocked by his violence, leaves. After Mark recovers and delivers his report to Gunnarson, the captain orders Barney's arrest and gives Cabot permision to print the story. When Barney learns that he is a wanted man, he disguises himself by donning a police patrolman's uniform, then arranges with a criminal named Manning to be smuggled out of the country. Barney agrees to hand over Manning's fee at a high school locker room later that night. When Patty tells Mark about her visit to the model home, he suspects that Barney hid the money there. At the locker room, after Barney delivers an envelope of cash to Manning's messenger, a heavily bandaged Michaels appears, draws his gun and tells the messenger to check the envelope. The "money" turns out to be cut-up newspaper. Michaels then chases Barney through the gym to a swimming pool. In the ensuing gunfight, Barney kills Michaels then drives to the house, where he is met by numerous police units blocking the streets. After shooting an officer, Barney runs to the house and retrieves the cash, but is surrounded by police. When he begins to fire at the officers, they respond with a hail of bullets, killing him.