American Marc Fraser and his French wife Fiona Marchand flee occupied France and the Nazi Gestapo to neutral Switzerland in 1943. With their backgrounds and language skills Allen Dulles, head of American OSS intelligence in Europe, recruits them as agents. Marchand goes to Italy to liaison with Italian partisans. Fraser works from Switzerland to recruit Germans willing to become intelligence sources for the Allies as German defeat becomes certain.
Fraser recruits a Nazi SS lawyer managing SS Swiss bank accounts as an intelligence source. Fearing capture and prosecution for war crimes, the lawyer succumbs to pressure to hand over control of the SS money when Germany surrenders in May 1945.
Post-WWII, Fraser and Marchand conspire with a Jewish British Army officer to use the SS money to finance smuggling of Jewish Holocaust survivors to Palestine. Fraser and Marchand then use the SS money to embark on a mission to uncover fugitive Nazi SS war criminals. Violent confrontations follow as they confront former SS attempting to escape to South America using ratlines operated by sympathetic Catholic clergy in Rome.