L'albergo degli assenti (1939)

A young lady is employed by a millionaire. She is kidnapped instead of the rich woman by a gang, on behalf of people who were interested in the rich woman's disappearance. She is brought to a special hotel, where the guests are people who are imprisoned because their families wanted to get rid of them. The rich woman is finally able to convince a police officer to investigate the strange vanishing. A prisoner goes mad and sets fire to the prison, which could not have been detected otherwise, freeing the disappeared at last.