This outing for our sleuth finds him working undercover - appropriately in a Panama hat shop - on a mission to help the US Government combat the activities of some spies bent on disrupting the movement of US Naval vessels though the Panama Canal. When a man is murdered in his shop, "Chan" is detained by the unwitting authorities who take him to a local jail where he, coincidentally, encounters no. 2 son "Jimmy" (Victor Sen Yung), who was working on a cruise liner and who is also stranded in Panama. Together, they must identify and thwart the would be saboteur amidst a plethora of suspects led ...