Season five picks up from events depicted in season four's flash-forward episode the seemingly peaceful Observers seized control of our universe in 2015. Now, in 2036, they have become ruthless rulers who stand unopposed. What awaits in the future, however, is the Fringe Team's final stand to protect our world.

The fourth season of the American science fiction television series Fringe premiered on Fox on September 23, 2011 and concluded on May 11, 2012, consisting of 22 episodes. The series is produced by Bad Robot Productions in association with Warner Bros. Television. The show was officially renewed for a fourth season on March 24, 2011.

Season three continues the rabbit-hole journey of three unlikely souls — FBI Agent Olivia Dunham, Fringe Scientist Walter Bishop and his jack-of-all-trades son Peter — through mind-bending investigations, parallel realities and threats growing in the borderlands between science and the unimaginable.

As the first season begins, FBI Special Agent Olivia Dunham is called in to investigate a mysterious outbreak that nearly kills her partner. The only person with any answers is an institutionalized scientist, Dr. Walter Bishop who can only be released under the care of his estranged son. Together, the three discover that the answer to this mystery is only a small piece of a much larger, more shocking truth.