Lansen, a German airline pilot employed by the British secret service, obtains aerial photographs of Russian missile sites. In Finland, he passes the film to his British contact who is then murdered by counter-espionage agents, and the film canister falls unnoticed to the ground. Leclerc, the head of British Intelligence, recruits and hastily trains Leiser, a young Polish refugee, to enter East Germany and verify the missile sites. Dropped near the East German border, Leiser is forced to kill a guard who stops him. Unnerved by the killing, he becomes careless and remains on the radio transmitter too long, allowing the East Germans to trace his location. Close to being caught, he is picked up by a truckdriver who threatens to turn him in unless he submits to his homosexual desires; Leiser instead murders the driver and uses the vehicle to escape. He picks up a woman hitchhiker and her small son, and at a roadblock, they become embroiled in a fight with the guards but are eventually released. Arriving at a small town, Leiser rents a room and again attempts to transmit a radio message, but the Germans trace the signal, locate Leiser, and kill both him and the woman, whom they believe to be his accomplice. At the conclusion, Finn school children are seen playing with the film, destroying the results of a complicated espionage maneuver.
