Marta, a maid at the boarding house run by her aunt Doña Laura, prevents the lodger Elena from committing suicide over the writer Arturo, who has proposed that they live together instead of getting married. Arturo then tries to seduce another lodger, the piano student Claudia, unaware that she is Elena’s younger sister. Claudia is not deceived by him, so he sets his sights on yet another lodger, the model Sara, during a party hosted by the elderly Requena, one of her suitors.