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&#39s 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.