Maria lives with her 18-year-old sister, Caterina in a small apartment, tutors her at home, lets her out only for dance classes. Yet Maria sees no reason to hide her work as a prostitute from her sister. Men come in and out of the apartment constantly, and Caterina turns up the volume on her music to drown out the sounds from the next room. The film soon reveals that the sisters are in love with each other, a situation that cannot stand, but exactly what prompts the characters' behavior is rarel...