On the French coast, unlucky Marie Galante (Ketti Gallian) is abducted and forced to board an American cargo ship bound for the Panama Canal. When an escape attempt leaves Marie high and dry in the Yucatan, she takes work as a nightclub singer to earn her safe passage to the Canal region. But Marie faces bigger problems when she gets mixed up in a destructive plot against the U.S. Naval fleet, and so she accepts the kindly assistance of secret agent Dr. Crawbett (Spencer Tracy).