To Catch a Spy

The film follows French secret service agent Walder as he investigates the theft of blueprints for an airplane made from ultra-secret metal. The plot thickens when these blueprints are believed to be in Switzerland, prompting another agent, Francis Coplan, to take action. Coplan's mission involves dealing with a man named Lindbaum, who has been double-crossed in a scheme involving international criminal Kalpannen.

As Coplan seeks to retrieve the stolen documents, he teams up with Heidi, a Swiss correspondent. Together, they uncover a web of deceit and danger as they attempt to identify the members of Kalpannen's gang, who have mysteriously turned up dead. This film is filled with action and suspense, typical of the era's spy genre, making it a notable entry in the Coplan series.