Martha and Félix are the children of the Butcher of Mons, a notorious Belgian serial killer from the 1990s. Unstable and riddled with insecurities, Martha lives vicariously through social media. Her brother, crushed by the family legacy, takes over their father's killings. Harassed and violently assaulted at work, the docile Martha falls into madness and goes through the looking glass into the strange and terrifying world inhabited by her brother.