Episode list

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. Lincoln Lee joins the Fringe team as they investigate a shapeshifter case that is very personal to him.

The "Over Here" team helps the "Over There" team look into a string of murders in which the victims are frozen from the inside out.

Two bullying boys die and exhibit an alarming state of rapid decay. Their would-be victim, an extremely lonely boy, has a remarkably unusual connection to the killer. Meanwhile, Walter fears for his sanity.

Olivia is haunted by an energy force that attracts metallic objects and Walter recalls his subject 9 that has the ability for astral projection. They chase the patient Cameron Jones but they conclude he is not the responsible for the energy force. However Cameron faces the force, something happens.

Shapeshifter Nadine hunts down a former Massive Dynamics scientist to help rectify her cellular translucence. Meanwhile, Peter finds conversing with Walter difficult.

The Fringe Division begins to wonder if Peter or his presence is behind a series of time displacements between 2007 and 2011. Walter imposes a self-exile to his bedroom.

A manhunt begins for an invisible killer who steals human pigmentation.

In an effort to find a way home, Peter journeys to the Other Side to confront Walternate. His venture proves more dangerous than expected. Meanwhile, Olivia receives a dire premonition from an Observer.

Peter'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.

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.

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.

Peter and the Fringe team take extraordinary measures in an attempt to stop life-threatening events.

The team hunts a killer who seems to be targeting couples - dehydrating the husbands and smothering the wives - with a very unusual motive. Peter and Olivia try to come to terms with her surfacing memories and emotions from the original time-line and the fact that she's beginning to forget parts of her life from the new time-line. Meanwhile, Walter and Peter try to figure out September's disappearance from the lab the week before.

An incident occurs that bears remarkable similarities to an early case in the original time-line, though there are some notable differences. Olivia's memories of the new time-line continue to fade, and Broyles places her on temporary leave, but her memories of original case assist Peter and Lincoln. Lincoln gets infected with a virus and Walter must figure out a cure.

Lincoln travels to the other side to join forces with Faulivia and his own alternate, as they search for a vigilante with a surprising connection to the shapeshifters.

When both of the two identities of people from the separate worlds experience the same catastrophes from incidents in just one world, the two Fringe teams collaborate. Walter crosses over to find that Jones is behind the phenomena, but to what ends? Also, the investigation into the Fringe-mole continues.

In the future, the Observers rule and humans that survived the purge serve them. There are still a small number of people fighting for the resistance, and one of them has discovered one of the original Fringe team in the form of Walter protected in amber. As the resistance attempts to get rid of the Observers, we get a glimpse into a rather dark dystopian future.

Multiple earthquakes are happening simultaneously around both our world and the alt-world. Walter believes he knows what the end game of David Robert Jones is. And, even though Olivia has a connection to one of the players Jones is using that she thinks she can utilize, in the end it leads to some hard decisions for the Fringe team.

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 worlds.

In the Season Four finale, the Fringe team is pushed to their breaking point as they desperately attempt to prevent a catastrophic event threatening the lives of everyone.