S1E15 · Inner Child

Just seconds before a building is demolished, a mysterious mute child that has been living alone underground is discovered. When the FBI's Fringe Division investigates, the boy forms an unspoken connection with Agent Olivia Dunham. Meanwhile, an especially gruesome serial killer resurfaces and showcases his "artistry" by displaying his work publicly. As the boy gradually assimilates into a new environment, Olivia and the team must race against the clock to prevent the mad man from causing further massacre.