The teams on the two worlds work together to solve the case of a shapeshifter, and Agent Lincoln Lee joins his world's team when no one remembers the existence of Peter Bishop.
Waltenate and his team call upon their counterparts from This Side for help when a serial killer goes on a bloody rampage. However, when they recruit the killer's This Side counterpart, a professor of forensic psychology, the team is forced to consider whether they can put civilians at risk.
As Walter tries to deal with his hallucinations, the Fringe team takes on a case of two 12-year-olds who died under mysterious circumstances after bullying another boy... and their bodies decompose at a remarkable rate of speed.
Walter is forced to leave the lab for the first time in years when he and Olivia go to Massive Dynamic to examine files that may connect one of Walter's Cortexiphan test subjects to a new series of crimes.
The translucent shapeshifters return to plague Fringe division, and a former Massive Dynamic scientist is involved. Meanwhile, Walter meets with Nina Sharp.
An electrical engineer and his wife, a professor of theoretical physics, are involved in a series of fatal time loop anomalies.
When a man mysteriously dies by an invisible force, his body rapidly begins turning ghostly white. The Fringe team learns that this is not an isolated incident, and there's evidence that links the predator to someone who passed away with an unknown genetic disorder. Meanwhile, Olivia suffers from migraines.
Olivia and Lincoln take drastic measures to deal with the looming threat from the translucent shapeshifters, while helping Peter find his way home. Something “over there” occurs that hasn't happened since the universes were linked at the end of last season.
The Fringe Division of the Other Side must deal with both a visit Peter and a new enemy.
Olivia continues to cope with the ominous warning from the Observers, while Peter and the team track a girl with the mysterious ability to predict death.
Our Astrid gets an unexpected visit from her Alternate, while Peter and Olivia track a killer using a toxin that has yet to be invented. Both universes collide in a case that pushes the boundaries of what is possible.
Peter, Olivia, and Walter come face to face with a mysterious and terrifying Fringe event as they get trapped in a town that there\'s no escaping from.
As the Fringe team investigates a mentally ill patient who appears to be connected to a series of murders, frightening clues and connections are uncovered that lead Olivia to some shocking revelations.
As David Robert Jones a captive Nina in an effort to activate Olivia's cortexiphan-enhanced abilities, the dying Observer visits Peter and Walter at their lab and Peter must merge minds with him to learn his secrets.
Following the recent shocking revelations and emotional events, Peter weighs his options as the Fringe team investigates a killer targeting love.
When a passenger on a Paris-to-New York flight transforms at the NY terminal and kills two TSA agents before dying himself, Peter realizes that the case is the same as one that he dealt with in the original timeline four years earlier. Meanwhile, Olivia is put on leave when Broyles discovers that 40% of her memories as an agent for him are now missing.
Lincoln travels to the other side to join forces with Bolivia and his own alternate, as they search for a vigilante with a surprising connection to the shapeshifters.
Walter travels to the Alternate Universe to assist in the investigation of a Fringe event with ties to both worlds. Meanwhile, David Robert Jones reveals his next target.
The FRINGE tradition of a mind-bending 19th episode continues as the story jumps ahead to 2036, when the Observers and the Fringe team engage in a game-changing battle.
The teams on both sides fight on for a common cause, and there are shocking developments tied to the Cortexiphan children.
A mysterious Fringe event causing people to spontaneously combust forces Walter to revisit his painful past while the Fringe team faces off against David Robert Jones to save the world, or world.
The Fringe team is pushed to the breaking point as they desperately attempt to prevent a catastrophic event that threatens the lives of everyone.