The movie opens in the seventeenth century with Charles Laughton as Sir Simon de Canterville. An act of cowardice sees him cursed to haunt the family castle until a relative performs an act of bravery. We move to 1943, when a group of American Rangers are housed at the castle, awaiting deployment in France. They're greeted by Lady Jessica de Canterville (the six year old Margaret O'Brien) who tells them the story of the ghost. One of the Rangers is Cuffy Williams (Robert Young), who turns out to be a direct descendant of the de Canterville family.
Based on a story by Oscar Wilde (although I doubt he envisioned the involvement of Nazis). If the idea of a cowardly ghost hasn't tipped you off, this is mostly a comedy. Laughton is fun as the ghost, O'Brien is staggeringly cute as Lady Jessica (she was apparently a popular and prolific child star), and Young is wonderfully charming as the man carrying both the movie and the fate of the family. Charming and funny.
Fans of this would probably also enjoy "I Married a Witch."