The Girl with the Jazz Heart.

When Miriam Smith's devoutly religious aunt and uncle insist that she marry pious Simeon Althoff, she answers an ad in a matrimonial newspaper and runs away to New York to meet her correspondent. Upon learning that Miles Sprague, the man in the ad, is coming to claim her, Miriam gets cold feet and begs her experienced friend Kittie Swasher, the hotel telephone operator, for help. When Miles arrives, Kittie pretends that she is Miriam and the three go to a cabaret. Meanwhile, the detectives employed by Miriam's aunt and uncle to bring her home appear and arrest Kittie, thinking that she's Miriam. Simeon arrives soon after and identifies the real Miriam, who is then taken home and locked in her room. Kittie and Miles follow and rescue Miriam, who realizes that she has fallen in love with the man from her ad.