The Fringe Division visits Massive Dynamic to see the Doomsday Machine and the presence of Peter assembles the device. He is submitted to tests by Dr. James Falcon against Walter's will. Walter asks Nina to find William Bell's research since he wants to restore his brain to increase his IQ and help Peter. Meanwhile, Broyles gives access to the mainframe where the alternate Olivia's files are to help the investigation and they suspect a mole is accessing the information. Soon they find that someone is killing the shapeshifters. Who might be the killer?
