Zeppelin

It’s 1915, Geoffrey Richter-Douglas (Michael York) is an Englishman of German descent, now a lieutenant in the British Army. His life changes as he meets Stephanie (Alexandra Stewart), a German Spy with whom he falls in love. She suggests him to come back to the fatherland where the members of his family and friends are. As a loyal soldier he reports this to his commanding officer, but surprisingly he also wants Geoffrey to go to Germany – on a secret mission to steal construction plans of the new type of Zeppelin LZ36 which is under development. Geoffrey leaves Britain undercover as a deserter (to make him more convincing) and soon arrives at Friedrichshafen where he meets his long time friend Prof. Altshul (Marius Goring) who lives with beautiful, much younger wife, Erika (Elke Sommer). Geoffrey learns that German intelligence didn’t bring him to Germany for the family reunion when he meets Colonel Hirsch (Anton Diffring) who insists that he must be aboard for the LZ36 maiden test flight; instead, he becomes involved after the flight tests in a military operation in which Geoffrey will play a key role. —Wikipedia