San Quentin is a 1937 Warner Bros. drama film directed by Lloyd Bacon and starring Pat O'Brien, Humphrey Bogart, and Ann Sheridan. It was shot on location at San Quentin State Prison.

Ex-Army officer Steve Jameson, chief guard at San Quentin State Prison, meets San Francisco night club singer May Kennedy. Her brother, Joe "Red" Kennedy, is on the run from the police and is arrested when he visits her.

Red arrives in San Quentin and fights hardened criminal "Sailor Boy" Hansen in the courtyard on his first day. Jameson punishes him. May begins a romantic relationship with Jameson, and finds out he is the yard captain in charge of the prisoners.

Jameson institutes a system to separate the hapless lawbreakers from the hardened criminals, and assigns Joe work outside of the prison in a road construction camp. Former chief guard Lieutenant Druggin resents Jameson, and surreptitiously assigns Hansen to the road camp as well. Hansen makes a plan to break out of prison. Red refuses to join him but changes his mind upon learning that Jameson is dating his sister.

Hansen's girlfriend arrives at the construction site and asks for help with a flat tire. Hansen volunteers and retrieves two guns hidden in the tool box. He and Red take a guard hostage and flee. After a car chase, Hansen's car crashes. He dies while Red escapes and goes to May's flat, but Jameson is already there. Red shoots at Jameson, slightly injuring him, and is shot by a police patrol. He has just enough strength to get back to the prison gates. Before dying, he asks the guards to tell Jameson he came back, and says the cons should respect Jameson.