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Season guide

Fringe: Season 4

22 episodes Premiered Sep 23, 2011 Updated Sep 22, 2026

Fringe Season 4 continues the overarching saga across 22 episodes. As part of Fringe Division, FBI agent Olivia Dunham uses experimental science to unravel the mystery surrounding a series of events. The series began as a traditional mystery-of-the-week series and became more serialized in later seasons. Most episodes contain a standalone plot, with several others also exploring the series overarching mythology. The

Previously on Fringe

Season 4 Lore Primer

Key plot threads, lore context, and character stakes you need to remember before diving into this season.

  • FBI agent Olivia Dunham uses experimental science as part of Fringe Division to unravel mysteries.
  • The series involves a brilliant but formerly institutionalized scientist working alongside the FBI.
  • The show features a mix of standalone plots in most episodes and others exploring the overarching mythology.
  • The overarching saga continues across multiple episodes involving strange phenomena and investigations.

Season overview

Fringe Season 4 continues the overarching saga across 22 episodes. As part of Fringe Division, FBI agent Olivia Dunham uses experimental science to unravel the mystery surrounding a series of events. The series began as a traditional mystery-of-the-week series and became more serialized in later seasons. Most episodes contain a standalone plot, with several others also exploring the series overarching mythology. The show follows FBI Special Agent Olivia Dunham, brilliant but formerly institutionalized scientist, and other members of Fringe Division as they investigate strange phenomena and question the answers across its run.

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Season 4 Episodes

Episode Guide

🛡️ SPOILER SHIELD

Season 4 Progress Shield

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Binge Efficiency Engine

Season 4: Filler vs. Essential Canon

Filter episodes by narrative weight. Focus on essential mytharc and skip standalone side quests.

23%
77%
Mytharc (5): Crucial lore & season climaxes
Core (17): Character development & subplots
Side Quest (0): Standalone / filler
S4·E1 Mytharc

Neither Here Nor There

Sep 23, 2011

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. Lin

S4·E2 Core

One Night in October

Sep 30, 2011

As the victims of a highly intelligent serial killer "Over There" stack up, the Fringe Division "Over Here" is asked to assist. As the two sides tangle and innocent people remain a

S4·E3 Core

Alone in the World

Oct 7, 2011

Two young bullies are found dead and in just a few hours they rot to an advanced state of decomposition. The Fringe team investigates and uncovers an amorphous figure claiming more

S4·E4 Core

Subject 9

Oct 14, 2011

Olivia uncovers a dangerous force that may be connected to past experiments with Cortexiphan. The investigation forces Walter to leave the lab for the first time in years and trave

S4·E5 Core

Novation

Nov 4, 2011

Olivia and the others of Fringe division attempt to determine the origin of Peter Bishop, who purports himself as Walter's son who had died as a young boy in the original time line

S4·E6 Core

And Those We've Left Behind

Nov 11, 2011

The Fringe team must find the pattern between tragic time loop anomalies. As the investigation unfolds, Raymond, an electrical engineer, and his wife Kate, a professor of theoretic

S4·E7 Mytharc

Wallflower

Nov 18, 2011

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 evidenc

S4·E8 Core

Back to Where You've Never Been

Jan 13, 2012

In an effort to find a way home, Peter journeys to the Other Side to confront Walternate. However, his venture proves more dangerous than expected. Meanwhile, Olivia receives a dir

S4·E9 Core

Enemy of My Enemy

Jan 20, 2012

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.

S4·E10 Core

Forced Perspective

Jan 27, 2012

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.

S4·E11 Core

Making Angels

Feb 3, 2012

Over Here 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

S4·E12 Core

Welcome to Westfield

Feb 10, 2012

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.

S4·E13 Core

A Better Human Being

Feb 17, 2012

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

S4·E14 Core

The End of All Things

Feb 24, 2012

The dying Observer comes to see Walter and Peter, who must take extreme measures to learn what secrets he hides and determine if he knows where Olivia is. Meanwhile, David Robert J

S4·E15 Core

A Short Story About Love

Mar 23, 2012

Following the recent shocking revelations and emotional events, Peter weighs his options as the Fringe team investigates a killer targeting love.

S4·E16 Core

Nothing As It Seems

Mar 30, 2012

The Fringe team faces a case that appears familiar to Peter. Strangely, it takes place in this timeline.

S4·E17 Core

Everything in Its Right Place

Apr 6, 2012

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

S4·E18 Mytharc

The Consultant

Apr 13, 2012

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.

S4·E19 Core

Letters of Transit

Apr 20, 2012

The Fringe team goes back to the future as the story jumps ahead to 2036, when the Observers and the Fringe team engage in a game-changing battle.

S4·E20 Core

Worlds Apart

Apr 27, 2012

The teams on both sides fight on for a common cause, and there are shocking developments tied to the Cortexiphan children.

S4·E21 Mytharc

Brave New World (1)

May 3, 2012

Walter is forced to revisit his painful past when a fringe event causes people to spontaneously combust; the team faces off with David Robert Jones.

S4·E22 Mytharc

Brave New World (2)

May 11, 2012

The Fringe team is pushed to the breaking point as they desperately attempt to prevent a catastrophic event that threatens the lives of everyone.