Inspired by actual events, Cloak and Dagger was first major "atomic power" melodrama of the postwar era. Gary Cooper stars as bookish physics professor Alvah Jesper, a character obviously based on A-bomb codeveloper J. Robert Oppenheimer. Pressed into service by the OSS in the last months of WW2, Jasper is sent to Europe in search of Dr. Polda (Vladimir Sokoloff), an atomic scientist held captive by the Nazis. In Switzerland, Jesper quickly runs afoul of enemy spies who murder the only person to know Polda's whereabouts. Moving on to Italy, he links up with the partisans, falling in love with gorgeous resistance fighter Gina (Lilli Palmer). Adopting a disguise, Jesper finally locates Polda and spends the last few reels in a desperate dash to freedom. Screenwriters Albert Maltz and Ring Lardner Jr. had originally intended Cloak and Dagger as a warning to a complacent America. Director Fritz Lang recalled in later years that, as conceived and filmed, the ending was to have occured after Jesper and a group of Allied soldiers stumbled upon the ruins of a secret Nazi A-bomb factory, as well as evidence that the German scientists had fled to parts unknown with their atomic secrets intact. "It's day one of the Atomic Age," Jesper was to have noted ruefully, "And God help us if we think we can keep it a secret much longer." This lengthy coda was removed from the final release print, transforming a thought-provoking drama into a mere romantic thriller.