Bill Skarsgård stars as Boy, a mayhem machine with a hilarious inner voice who’s been trained from childhood by his mentor (Yayan Ruhian) to assassinate the bloodthirsty Hilda Van Der Koy (Famke Janssen) and avenge his family’s murder. Guided by his little sister’s prankish spirit, Boy uncovers one stunning revelation after another as he barrels toward Hilda, leading to a shocking, carnage-crazed finale.