When a strange parasite attaches itself to the internal organs of a dying FBI agent, Olivia suspects a connection to the Pattern; Peter and Walter tap into a dead man's brain waves.

When the Fringe Division delves into another bizarre occurrence aboard an international jumbo jet, freakish remains are discovered at the crash site. Memories tip the team toward some promising leads, but the bigger picture and mysterious threat eludes them. With limited options and insufficient intelligence, Olivia and Peter go undercover.