Beautiful Russian spy Sonja Baranikowa (Gerda Maurus) seduces Colonel Jellusic (Fritz Rasp) into betraying his country for her employer, Haghi (Rudolf Klein-Rogge), a seemingly respectable bank director who is actually the criminal mastermind of a powerful espionage organization. Jason (Craighall Sherry), head of the Secret Service, gives the task of bringing the mysterious Haghi down to a handsome young agent known only as Number 326 (Willy Fritsch) who believes his identity is a secret. Haghi is well aware of him and assigns Sonja to worm her way into 326's confidence; Sonja convinces him that she has just shot a man for trying to rape her and he hides her from the police.