Walter thinks the abduction of a young music prodigy is linked back to his old bunkmate at St. Claire's Hospital. When he kidnaps the child he sees a sequence of flashing lights. Olivia wants Walter to return to the mental institution much to Peter's outcry, but Walter's determination to help ends up having chilling ramifications.

Two young bullies are found dead and in just a few hours they rot to an advanced state of decomposition. The Fringe team investigates and uncovers an amorphous figure claiming more victims. Walter becomes increasingly distracted with his mental state.