Toward the end of World War II, the Allied secret service receives a partial message indicating that the Germans are researching nuclear energy to build atomic bombs. In Midwestern University, the scientist Alvah Jesper is called up by the Office of Strategic Services (OSS) to meet his former colleague Dr. Katerin Lodor in Switzerland and bring her to North America. However, his mission fails and Dr. Lodor is killed by the Nazis but first she informs Alvah that his acquaintance Dr. Giovanni Polda is working for the Nazis in Italy. Dr. Jesper travels to Italy and with the support of the Italian partisans led by Pinkie and Gina, he has a meeting with Dr. Polda that is under the surveillance of the Gestapo. The scientist tells him that his daughter Maria had been abducted by the Gestapo and Alvah makes a deal with Dr. Polda, promising to release Maria first and bring them to North America. While Pinkie travels to rescue Maria, Alvah stays with Gina and they fall in love with each other.