Helen Roberts, who's on probation, goes back to work as a waitress at Torre's Fish Palace, a San Francisco waterfront dive. The customers are low characters trying to make time with Helen and ex-rum runners trying to make a dishonest dollar. Some of the latter, including Helen's unwelcome suitor Martin Rhodes, are after a mysterious, valuable hidden "cargo"; when violence erupts, Helen finds herself innocently involved, and is soon on the run from both cops and crooks.