Near the end of World War II, the Allies must find out how much the Axis knows about building atomic bombs. The OSS recruits a physicist, Alvah Jesper, to reach his former colleague, Katerin Lodor, now in Switzerland, and bring her out for debriefing. He reaches her, but a German agent is quickly onto him, and Lodor dies. Jesper must now get into Italy, go underground with the help of Gina, a resistance leader, and convince Polda, a physicist there, to leave with him. Polda won't go until his daughter is rescued from German detention. As Jesper's pal Pinky works on rescuing Polda's daughter and as time for escape runs down, Jesper and Gina fall in love.—