Fringe — Season 4

Just one week after Peter Bishop saved the day and was then wiped from existence, the truce between the two worlds remains intact and the two sides are forced to work together. Meanwhile, Lincoln Lee joins Fringe Division as they investigate a shapeshifter case that is very personal to him.

As the victims of a highly intelligent serial killer stack up in the Alternate Universe, the Fringe Division "over here" is asked to assist. As the two sides tangle and innocent people remain at risk, the suspect's doppelganger, a professor who teaches Forensic Psychology, is brought into the fold and forces the team to consider the notion of sending civilians to the other side.

The Fringe team investigates when the bodies of two 12-year-olds are found in an advanced state of decomposition just hours after they were last seen bullying another boy. Meanwhile, Walter becomes increasingly distracted by his hallucinations.

Olivia uncovers a dangerous force that may be connected to Walter's past experiments with the drug Cortexiphan. Their investigation forces Walter to leave the lab for the first time in years as he and Olivia head to Massive Dynamic in New York to examine old case files. Walter struggles with life outside the lab as he confronts the demons of his past.

As the threat of the translucent shapeshifters intensifies, former Massive Dynamic biochemical researcher Malcolm Truss enters the fold. Meanwhile, Fringe Division attempts to determine the origins of Peter Bishop, Olivia experiences an unexplained time fluctuation, and Nina Sharp pays Walter a visit in the lab.

Peter is still being held by Fringe Division who have yet to fully trust him, so when a pattern of tragic time loop anomalies emerges, the team begin to wonder if Peter's unexplained appearance is responsible. Meanwhile, Walter still doesn't believe that Peter is his son, and Peter attempts to explain his relationship with his Olivia to the Olivia of this timeline.

While Olivia struggles with migraines, Fringe Division investigate an invisible force which kills its victims and causes the body to turn a ghostly white. As they trace the pattern of deaths, the team discovers that the force is linked to someone who died of an unknown genetic disorder.

In an effort to find a way home, Peter journeys to the Alternate Universe to confront Walternate. The venture proves more dangerous than expected when Peter finds himself unexpectedly thrust into the conflict posed by the human shapeshifters. Meanwhile, Olivia receives a dire premonition from the Observer, September.

Peter and Lincoln's visit to the other side intensifies as the Alternate Fringe Division faces off against a formidable new foe in a harrowing race against time. Meanwhile, Walternate and his wife Elizabeth discuss how best to help Peter return to his own timeline.

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. Meanwhile, Olivia continues to struggle with memories belonging to the Olivia of Peter's timeline.

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 uses a captive Nina in an effort to activate Olivia's Cortexiphan-enhanced abilities, a dying Observer appears in the lab and forces the Fringe team to take extraordinary measures in an attempt to stop life-threatening events.

Fringe Division investigates a suspect who is using pheromones to replicate love... but who is killing couples who are in love in order to obtain it. Meanwhile, Olivia tries to deal with the onslaught of memories from her other self, and Peter considers his options in his continued attempt to return to his timeline.

Olivia, having willingly accepted the replacement of her memories with those from Peter's timeline, is put under psychiatric evaluation and Lincoln Lee is put in charge of the team in her absence. Under Lincoln's leadership, Fringe Division investigates a case that is eerily familiar to one from the original timeline.

Heading over to the Alternate Universe, Agent Lincoln Lee and the other Fringe Division track a vigilante who is leaving mutilated corpses in his wake, only to discover a hidden connection to the shapeshifters both universes have been hunting.

Walter travels to the Alternate Universe to assist in the investigation of a Fringe event with ties to both worlds. Meanwhile, Alternate Olivia continues her investigation into those responsible for Captain Lee's death, and David Robert Jones reveals his next target.

The Observers, no longer content with observing history, return to the past and stage an invasion of 2015, transforming human society in a totalitarian state under their control. In 2036, FBI Agents Simon Foster and Etta Bishop begin a desperate search for the original Fringe team as the human resistance movement sets the stage for a game-changing battle with the Observers.

When multiple earthquakes strike simultaneously across the globe in both universes, the Fringe teams on both sides unite in their quest to defeat a common foe. As time counts down, the fate of both universes hangs in the balance.

When a mysterious Fringe event suddenly causes people to spontaneously combust, Walter is forced to revisit his painful past while Fringe Division faces off against David Robert Jones to save the world, or worlds.

Pushed to breaking point, Fringe Division desperately attempts to prevent a catastrophic event orchestrated by David Robert Jones and his hidden associate, Dr. William Bell. Meanwhile, the Observer known as September arrives with a dire warning that will alter the course of humanity's future.