MA MERE takes place in the Canary Islands, where the film's family shares a home. The mother Hélène (Isabelle Huppert), cool and in charge, and her teenaged son Pierre (Louis Garrel), a pious Catholic back from boarding school, discuss his father's infidelity; the next they hear, he is dead in a car crash. Hélène launches into a wild series of parties, gradually involving her son in her drugging, drinking and sex-fuelled nights out. When she mysteriously goes away, her son is left in the care of her mistress Réa (Joana Preiss) and Hansi (Emma de Caunes), an icy blonde sadist with whom he falls in love. As the film evolves, we realize that this is a period of initiation for the young man until his mother can return and fully bring him to sexual maturity and adulthood.