A killer hides out in a small-town boarding house.

It is the Christmas Holidays and reformed thief, Boston Blackie goes to Castle Theater to pick up players who will perform for prisoners that are still in prison. He takes a girl with him who has a brother already in prison. She has visited the prison twice in the month, so is not suppose to visit again. However when the group is completed the girl is included as well as Inspector Farrady. One of the clowns in the show is kidnapped and replaced by a con who wants to get even with two ex-partners. Boston Blackie figures out that a con has replaced one of his clowns but is unable to stop him. Blackie's clothes are stolen and a murder is committed. Of course, the Inspector immediately suspects Blackie of being involved. Now it is Blackie's job to find the killer, exonerate himself and help the girl free her brother.

On December 6, 1941, Captain Yamanada of the Japanese aircraft carrier "Hiranamu", orders full steam ahead for Pearl Harbor. His ship encounters and sinks an American yacht and the single survivor, Sue Curry, is rescued by an American submarine, the "Sea Serpent", commanded by Commander Chris Warren. He hears her story and attempts to radio a warning to Pearl Harbor. Yamanada, hearing the signals, orders the airlines jammed, and then sends his son into the air to sink the sub. The attack fails, after the sub makes a crash dive, but they fail in their warning attempts. The next morning, December 7th, the men on the sub hear the story of the bombing of Pearl Harbor, and devise a desperate plan to sink the Japanese carrier by letting the carrier know their position. The carrier comes in search of the submarine.

Song and comedy revue, featuring Western talents, along with a theatrical troupe taking their vacation on the Lazy B Ranch run by Steve Bradley. Steve is about to enter the army and he and Tex Coulter compete for the love of Connie Grey.