San Francisco Docks Dec 25, 1940

Longshoreman Johnny Barnes is in love with Kitty Tracy, barmaid at her father's waterfront saloon, and he beats up Cassidy, a crooked politician who has been annoying her. Cassidy is murdered that night and Johnny is jailed for the crime. Kitty, her father Andy Tracy, and waterfront-priest Father Cameron believe Johnny is innocent but all evidence points to his guilt.