Sluggishly paced yet effective melodrama finds willful provincial girl, studying math in Berlin, picked up by rich dandy twice her age at a Mozart concert. He makes her a proposition that'd send most country virgins running for the hills: he's only in town for a couple weeks, it's unlikely he'll ever return, would she care to be his mistress for that time? Not always brilliant, but gets inspired towards the end.
Protofeminism thwarted by a catch. But the final scene makes us forget the identity struggles... (I guess the image above is from Ariane, jeune fille russe, French-language version of the same film directed by Czinner as well in 1931 - and not the one stared by lovely Elizabeth Bergner).