Under the Family Tree (2017)

Because of trouble at school, 16-year old Isabell's single mum persuades her to take part in a self-knowledge seminar in the Sudeten Mountains. What begins as an unusual holiday adventure in an esoteric group, changes when one of the participants has a mental breakdown and disappears. Has the young woman left or is she the victim of a crime? Isabell is alarmed and begins to investigate the seminar and the other members. Her enquiries are met with a wall of silence. When the mutilated body of the woman who disappeared turns up, Isabell's stay at the wildly romantic resort becomes a nightmare.

Unfortunately the movie Under the Family Tree is not yet available on HBO Max.