The Locked Door is a 1929 American pre-Code drama film directed by George Fitzmaurice, and starring Rod LaRocque, Barbara Stanwyck, William "Stage" Boyd and Betty Bronson.

Ann Carter, an inexperienced young woman, accepts an invitation to dinner from her employer's son, Frank Devereaux.

It is aboard a "rum boat", a ship sailing beyond the 12 mile limit to get around the restrictions of Prohibition.

They are about to celebrate their first wedding anniversary when Frank resurfaces in Ann's life, this time as the boyfriend of her naive young sister-in-law, Helen.

To protect her husband, Ann phones the switchboard operator and reenacts her earlier assault, ending with her firing two shots.