Renatus, a former math teacher, is forty years old and lives with his mother in a desolate block of flats. Ever since his early youth, women with big breasts have fascinated him, because they symbolize a kind of earth mother to him. He has never had an especially close relationship with his own mother; she was too “bony” for him.
The object of Renatus’ fantasy is the actress Senta Berger, to him everything a woman should be. Standing at the blackboard and explaining the mathematical laws of sine and cosine (in Latin sinus means “bosom”), Renatus sings the praises of female curves and those of Senta Berger in particular. Filmmaker Ulrich Seidl let the former teacher speak freely about his obsessions and desires, intercutting the protagonist’s monologues with scenes from his day-to-day life.