One of the better entries in the series finds Charlie in Panama hunting down a spy ring determined to blow up the U.S. fleet as it travels through the Panama Canal. He’s “helped” by number two son Jimmy (Victor Sen Yung).
A sea plane on its way to Balboa has an interesting group of passengers. They include British thriller writer Clivedon Compton (Lionel Atwill), Chicago school teacher Jennie Finch (Mary Nash), Viennese biologist Dr.Rudolph Grosser, American Richard Cabot (Kane Richmond), Singer Kathi Lenesch (Jean Rogers), night club owner Manolo (Jack LaRue) and secret service agent Godley (Addison Richards).
Alerts are out to stop anyone taking pictures of the fleet. A man disguised as a fisherman tried it and had to jump in the water and swim away before bullets stopped him. Kathi gets a job at Manolo’s club. She escaped her home country ahead of the Nazi invaders.
Godley drops by a shop that sells Panama hats. It’s owner by Fu Yuen. It’s really Charlie undercover. Godley has a clue to notorious spy Reiner. He lights up a smoke and is about to tell Charlie what he found out when he keels over dead. Charlie is arrested and tossed in jail. To his surprise one of the other inmates in son Jimmy. He was working as steward on a boat during the summer break from college.
The local governor gets them out of there. Jimmy is anxious to help his Pop and he’s told to investigate Dr.Grosser. Jimmy studied him in college and is afraid because of the germs Grosser works with. He follows Grosser to his apartment which is in the tobacco shop owned by Achmed Halide. It’s across the street from the hat shop.
Jimmy overhears Clivedon ordering a special mixture then he investigates Grosser’s place. He finds a lab complete with rats infected with Bubonic plague. Jimmy rushes to Manolo’s club where Charlie is keeping an eye on things. A sailor grabs Kathi after her number and starts dancing with her. He calls for the MP’s when she asks what time the fleet is due. Before that’s straightened out Jimmy blabs the Fu Yuen is really his Pop.
As things move along Clivedon is found murdered in his hotel room when Jimmy opens a closet door. He’s not the last one to be killed.
Later, Miss Finch tells Charlie she hears groaning sounds coming from inside a tomb. He goes in and finds a man tied and gagged. It’s Jimmy. Miss Finch goes in with him along with an MP. They discover a basement room when Jimmy falls through a secret panel. There are cans of explosives. Some are empty. Charlie knows what that means. When he tries to leave he discovers that they’re all locked inside.
If you’re used to movies like this you’ll know who Reiner is but it’s still a good one.