During the onset of World War II, Czech scientist Dr. Alfred Bomasch escapes a Nazi concentration camp and seeks refuge in Britain with his daughter Anna. The Nazis, determined to retrieve Bomasch and exploit his knowledge for their war efforts, kidnap Anna and take her to Germany. British intelligence officer Gus Bennett, posing as Nazi official Karl Marsen, embarks on a dangerous mission to infiltrate Nazi ranks and rescue Anna. Their journey takes them across various European locales, involving numerous close encounters as they remain one step ahead of the pursuing Gestapo.

Back in Germany, Anna and her father are reunited but remain under constant threat. Utilizing espionage tactics and unyielding determination, Bennett strategically maneuvers through perilous situations to rescue the Bomaschs. Tense cat-and-mouse chases, deceptive disguises, and daring maneuvers highlight Bennett's struggle against time and enemy forces. The final leg of their escape hinges on a suspenseful cross-country journey, testing their skills and resolve at every turn.