A gambler investigates his baker's murder and learns of a Nazi spy ring that he manages to capture with help from fellow gangsters.
Boss Gloves Donahue (Humphrey Bogart) makes bets on sports. Baker Herman Miller (Ludwig Stossel) tells Pepi (Peter Lorre) he won't spy anymore for murderers, and Pepi beats him. Donahue's mom (Jane Darwell) summons him, because Miller is gone. Donahue finds him dead, and a blonde asking for him disappears as Lt. Forbes (James Burke) tells Donahue not to leave. Marty Callahan (Barton MacLane) calls Donahue to remove his mother. Donahue's driver Barney (Frank McHugh) says he got married. Donahue finds the blonde Leda Hamilton (Kaaren Verne) singing and sends his mom home but tells Joe (Edward Brophy) he won't leave yet. He questions Leda about Miller and quarrels with Pepi. Joe and men make Donahue leave; but he comes back and finds Joe shot and dying. Donahue tries to find the cab and hears on radio that Callahan accused him of killing Joe.
Donahue and Sunshine (William Demarest) search a building, and Sunshine is abducted. A man shoots at Donahue, and they fight until the man falls to his death. Donahue and Barney go around the corner to an auction at a museum conducted by Ebbing (Conrad Veidt). Donahue bids $3,000 and asks Ebbing for Leda, but she knocks him out. Barney is forced to leave by Madame (Judith Anderson), who warns Leda; but she helps tied-up Donahue and Sunshine. They get away from Pepi and look around, learning of the fifth column for Hitler. Donahue captures Ebbing with Leda; but Ebbing hits the alarm, and Donahue knocks him out. Donahue makes Leda escape with him and Sunshine. Barney drives as they are followed. They stop and fight as Donahue runs off with Leda, who says she does it because her father is in Dachau. While Donahue fights a man, she reads on a paper her father is dead.
Donahue and Leda take a room and send for the police; but Ebbing captures them for the police. Donahue and Leda explain to Lt. Forbes, but at the museum evidence is gone. So Donahue escapes. Callahan breaks in on Donahue's people, and Donahue tells of spies. Leda is bailed out by Pepi. Sunshine tells Donahue, and they follow them. Donahue and Sunshine knock out two men and replace them in a meeting as Ebbing explains the plan; Donahue has to make a report. Pepi sees him and tells Ebbing, who is interrogating Leda. Callahan and Barney arrive with a mob that rushes in with clubs to knock heads. Pepi refuses to go with Ebbing, who shoots him. Donahue finds a boat; Ebbing captures him and orders him to drive the boat into a battleship; but Donahue veers off to a lumber boat. In the final scene Lt. Forbes tells Donahue he is free.
Humor spices up this propaganda drama with many plot
twists as a bookie and gangsters unite with police to knock the
nasty Nazi's "back on their Axis."