Cloak and Dagger 1946

In 1944, a handsome bachelor and nuclear physicist named Alvah Jesper [Gary Cooper] is working in the United States on the Manhattan Project to build a nuclear bomb. Recruited into the Office of Strategic Services, his mission is to make contact with a Hungarian nuclear physicist, Katerin Lodor [Helene Thimig], who has been involved with the German project and has fled to neutral Switzerland. Flown into Switzerland, Alvah discovers the country is teeming with German agents who, after a single brief conversation with Katerin, abduct her. By befriending and then blackmailing Ann Dawson [Marjorie Hoshelle], an attractive American who has become a German asset, he learns where Katerin is being held, but an OSS raid on the building fails and Katerin is shot dead.

In the conversation, Katerin had indicated that the Germans want her to work with an Italian nuclear physicist named Polda [Vladimir Sokoloff]. The OSS then lands Alvah in Italy from a British submarine, where he is sheltered by the Resistance fighter Gina [Lilli Palmer]. He manages a brief discussion with Polda, who agrees to cooperate with the Americans only if the OSS first frees his daughter Maria, who is being held by the Germans. The OSS raid on the building succeeds, and in a nearby safe house they deliver Maria to her father. He is horrified, because the woman isn’t his daughter but a German agent, and the house is surrounded by German troops. In the ensuing gun battle, Alvah and Gina smuggle Polda out through a tunnel from the house to a nearby well and press on across the countryside to a rendezvous with a British aircraft that will fly them out. Polda and Alvah board it safely; although there is room for her, Gina chooses to stay behind to help free her country from the Germans and begs Alvah to return for her when the war is over.