Boy Kills World stars Bill Skarsgrd as a deaf and mute fighter seeking bloody vengeance for the murder of his family. His targets are the ruthless van der Koy siblings. They rule a post-apocalyptic city with an iron fist. Famke Janssen co-stars as Hilda van der Koy, a paranoid and psychotic tyrant hellbent on finding a long-lost enemy. Brett Gelman portrays Gideon, Hilda’s younger brother. He writes scripts for their theatrical massacres, which are directed by Melanie van der Koy (Michelle Dockery), the middle sister and true brains behind the cruel dynasty.