When Paul spots his childhood sweetheart on the street in Berlin, she seeks his support, but US agents appeal to Paul.s patriotism to find out her secret.

When he meets American agent Mike Allen (Macdonald Carey) in Spain, Paul is asked to help determine whether a girl he knew in Berlin, Erica Voss (Janine Gray), is an enemy agent. When their private plane crashes in the desert, the truth about her is revealed.