The Strange Door (1951)

This period drama crossed with a gothic horror film was entertaining because of Charles Laughton. He chewed up every line of dialogue in the most delightful way. His evil character's demented plan for revenge took 20 years to materialize. He kept his brother in the dungeon and his niece in the castle the whole time. No spoilers. It's not a great movie, but Laughton is worth watching at his most wacky: the evil cackle is something! Boris Karloff is underused.