San Quentin is stark, authentic-looking prison melodrama that misses being big entertainment because of a love story that is none too strong and a plot [by Robert Tasker and John Bright] that is only moderately forceful.
Various scenes were made in and around the San Quentin pen. Those which are of the prison and not staged were shot at a distance so that no prisoners could be recognized.
The only time when the camera isn’t in the prison or with Warner-hired players doing the convicts (large mobs having been used for some sequences), is when the story is with the girl, a cafe singer whose brother is in stir. Majority of the action is assigned to convicts and prison officials, guards, etc.
Romantic leads are Pat O’Brien and Ann Sheridan, while the girl’s brother is Humphrey Bogart, a tough convict, and a guard of the old school is played by Barton MacLane. All turn in good jobs.