Obscene: The Case of Peter Herzl (1981)

Peter Herzl, social worker and Left sympathizer from Wuppertal, West Germany, is assaulted and robbed on the way back from Yugoslavia to his home country. Due to a misunderstanding, the police mistakes him for a left wing terrorist. He finds shelter in Vienna with a tough but loving sex-show actress/prostitute called Kathi, who falls for him. Since he likes her as well, they end up having sex in her apartment. However, Kathi's adolescent daughter, Edeltraud, who's in a possessive incestuous psycho-sexual relationship with her mother, arrives home and catches them in the act. Hurt and shocked, she runs away to her room. Kathi goes after her to calm her down with some sex. Peter finds this bizarre situation strangely compelling and, after Edeltraud becomes used to him and starts liking him, they eventually become a weird happy incestuous surrogate family. Meanwhile, the search for Peter, led by a sexually frustrated elderly commissioner, is at full speed and Kathi's greedy pimp sees this as an opportunity to get easy money by betraying her.