In the 1930s, amoral blonde tommy-gun girl Bonnie Parker cut a swath of bodies across the South-West. Starting out on gas stations and bars with side-kick Guy Darrow she graduated to bank hold-ups with Darrow's brother and, after bloodily springing him, her jailed husband. But there was never any doubt who was in charge.

Biff Jones is a driver/salesman for the Good Humor ice-cream company. He hopes to marry his girl Margie, who works as a secretary for Stuart Nagel, an insurance investigator. Margie won't marry Biff, though, because she is the sole support of her kid brother, Johnny. Biff gets involved with Bonnie, a young woman he tries to rescue from gangsters. But Biff's attempts to help her only get him accused of murder. When the police refuse to believe his story, it's up to Biff and Johnny to prove Biff's innocence and solve the crime.