Olivia and Nina have a discussion about the First People books. Olivia mentions she read Fauxlivia's journal and Nina feels for her. Thinking Peter might have also developed feeling for Fauxlivia because she is a "better me", Nina tells her she has always regretted that she and William Bell never shared their true feelings. She encourages Olivia to talk to Peter.
The case of the week is a delivery of a creepy little doll delivered to a scientist, at his office, on his birthday. It spurts out a substance that removes bones from the body. The suspect is found, he flees and is hit by a car. He is in a coma and with the amount of neural activity, Walter thinks he knows a way to question him. The suspect was a part of a science project and his wife and the wives of others who tried to start a family who were in a project all had pregnancies end with miscarriages. The babies had no skeletons.
Walter connects the case to another child who was used by Walter and William Bell to test Cortexiphan, as they did on Olivia. Simon can read minds, so it is Walter's hope he can hear the thoughts of the suspect. He does hear disjointed thoughts and it leads the FBI to more suspects.
Simon and Olivia go undercover, find and stop the new suspects and save hundreds from dying in another attack.
Nina figures out who wrote the book. Sam Weiss. He has been in numerous other episodes so has a history with Fringe Division. He Tells Nina that Peter is finely tuned to the device and it can be a device of creation or mass destruction, depending upon his mood. And those moods are based solely upon whether he chooses Olivia or Fauxlivia. As Nina is being told this, Olivia reads a note Simon gave to her of Peter's thoughts. "He still has feelings for her."