Almost a Lady.

Marcia, a pretty young girl, goes to work as a model for a lecherous dress-shop owner. She resists his advances, despite his giving her expensive gifts. One day Mrs. Reilly, a prominent society woman and a customer of the shop, invites Marcia to a party she's throwing. Marcia winds up impersonating a famous writer in order to impress a "duke" for Mrs. Reilly, who doesn't know the "duke" isn't really a duke. Complications ensue.