The trendy elegance of director Douglas Sirk's later big-budget soap operas is nowhere to be found in Sirk's Atomic-Age melodrama Mystery Submarine. MacDonald Carey stars as Brett Young, a U.S. undercover agent whose job it is to prevent atomic secrets from falling into the wrong hands. Marta Toren co-stars as Madeline Brenner, a woman of mystery who is seemingly in cahoots with enemy agents. The film's "maguffin" consists of the top-secret info stored within the brain cells of scientist Adolph Guernitz (Ludwig Donath). The titular mystery submarine figures into the film's climax, which takes place just off the coast of Mexico.

Sharon is a seemingly contented suburban wife with a nice husband, house and family, until she discovers that her husband is cheating on her with the neighborhood nympho.

Casanova, a young patriot in 18th-century Sicily, upon learning that his father and sister have been murdered, returns to Palermo and engages in guerilla tactics against the forces of the Governor. Lady Bianca, the Governor's daughter, is in love with one of the patriots, Lorenzo, and desires to escape from the palace. Her lady-in-waiting, Zanetta, enlists the aid of Casanova and he rescues them and takes them to the partisan's camp. The rebels are victorious. Lady Bianca makes plans to marry Lorenzo, and Casanova and Zanetta have similar plans.

The Cisco Kid and his buddy Gordito arrive in town and learn that Cisco is supposedly dead. Not only that: Before his death, he is believed to have attempted to steal Susan Wetherby's land.

Ship engineer Jim Taggert is rescued from a torpedoed tramp steamer by Joe Morgan, an American gangster that found New York too hot for him, and has become a fisherman operating from an out-of-the-way island off of the coast of South America. Morgan makes his headquarters at the Halfway House run by the parents of Maria Styx as a bar and dance resort catering to the planters and traders of the island. Taggert finds himself practically a prisoner along with a group of American girls acting as entertainers at the resort. Taggert shadows Morgan in his activities in a remote cove and finds that Morgan is supplying German U-boat commanders with torpedoes, but does not know that Morgan has rigged the torpedoes with clock devices that explode when at sea and sinks the U-boats.

Northern lawyer John Reynolds travels to New Orleans to try and clean up the local crime syndicate based around a lottery. Although he meets Julie Mirbeau and they are attracted to each other, the fact that her father heads the lottery means they end up on opposite sides. When her father is killed, Julie becomes more and more involved in the shady activities and in blocking Reynolds' attempts at prosecution.

1944 Mexican film directed by Miguel M. Delgado

Bill Burnett, a resident of Bali, visits New York City, meets and falls in love with Gail Allen, the successful manager of a Fifth Avenue shop, who is determined to remain free and independent. Bill proposes, Gail declines and Bill goes home to Bali. But a young girl, Rosie, and Tony the Window Cleaner, who dispels advice on every floor, soon have Gail thinking maybe she was a bit hasty with her no to Bill's proposal. Ere long she discovers that she does love Bill and can't live without him. She goes down to Bali to give him the good news. He learns that he is soon to marry Noel Van Ness. She goes back to New York City.

Cisco saves a stagecoach from being robbed and takes a shine to one of the passengers whose father is in cahoots with a vicious criminal who plans to murder him.