Little Miss Broadway (1947)

She's the upstart who upset cafe society!

Upon leaving finishing school, Judy Gibson goes to meet her presumed wealthy and socially prominent relatives. However they are penniless Broadway characters and take possession of a Long Island mansion owned by an incarcerated thief so Judy doesn't find out the truth. Judy arrives with her fiancé and his father, who tries to sell worthless stock to Judy's family. They give him $200,000, part of the stashed loot they found belonging to the home-owner thief.