In order to replace her memories with her alternate counterpart, Olivia undergoes experimental treatment in the parallel universe. She struggles to find a way to transport between universes but she was left imprisoned in “Over There”. She manages to get into a safe house, which turn out to be the home of her mother, who died in the parallel universe. Meanwhile, Walter and Peter get on with their lives, not suspecting that the Olivia with them is her disguised alternate counterpart.

The Fringe Team investigates a mysterious box which causes people to be in a trance like state that ultimately leads to their death. Peter manages to disable the device.

In the parallel universe, Olivia works at a case in which a series of events lead to deadly incidents. The target Milo, plans to kill Olivia in an accident, but was unable to do so because Olivia is from a parallel universe.

Olivia is determined to uncover details about a serial kidnapper “over there”, finds Henry in the process and asked for his help on her mission to return home. The Fringe team finds out about a device that can communicate between universes. Olivia found a way to return to her universe and tells a cleaning lady to warn Peter that she is trapped in a parallel universe before Walternate pulled her back. She ultimately finds herself in grave danger in the parallel universe.