When a pair of teenage girls attack one another, each believing the other to be a monster, Mulder and Scully find that their investigation could possibly lead back to their long-lost son, William.

Cast: David Duchovny, Gillian Anderson, Mitch Pileggi, Madeleine Arthur, Robyn Bradley, William B. Davis, Louis Ferreira, Eddie Flake, Sarah Jeffery, Mackenzie Murdock, Chanelle Peloso, Sunita Prasad, Miles Robbins, Zak Santiago, Troy Anthony Young