"The Day We Died" is the third season finale of the Fox science fiction drama television series Fringe. It is the season's 22nd episode and the series' 65th episode overall. The finale follows the aftermath of Peter Bishop entering and activating the doomsday device, events which took place in the previous episode. He finds himself 15 years in the future; though the device has destroyed the parallel universe, his universe is nevertheless gradually disintegrating. Peter comes to realize the background of the doomsday device and wakes up in 2011. After getting the two universes to agree to work together, he inexplicably disappears.
The episode's teleplay was co-written by Jeff Pinkner and J.H. Wyman, while Pinkner and Wyman co-wrote the story with consulting producer Akiva Goldsman. Executive producer Joe Chappelle served as director. The writers wrote the script without knowing if the series was going to be renewed for a fourth season; Fox's renewal announcement came in late March, but no changes were made to the storyline. They designed the episode as a set-up for the following season, equating it to a book chapter that "propels" the reader forward. Unlike previous season finales, "The Day We Died" was one hour long and was linked to the previous two episodes in one continuous story arc. "The Day We Died" featured one-time guest actors Brad Dourif and Emily Meade.
"The Day We Died" aired on May 6, 2011 in the United States to an estimated 3.0 million viewers, though this number almost doubled once time-shifted views were taken into account. While its 1.4 ratings share among adults 18 to 49 was an eight percent decrease from the previous episode, it helped Fox tie for first place that night. Reviews of the episode have been generally positive, with many critics writing that Peter's disappearance was a good direction for the series. Multiple reviewers ranked it as one of the best episodes of the television season, including The Futon Critic and TV.com. The cast were also receptive to the episode, and actor John Noble submitted his performance for consideration at the 63rd Primetime Emmy Awards.
Plot
In May 2026, the prime universe is suffering from the same singularities that have already destroyed the parallel universe, as a result of the two universes being inextricably linked together. Though the Fringe Division that developed in this universe has been able to use amber to contain these vortices, a group called the "End of Dayers", led by a man named Moreau (Brad Dourif), attempts to breach the fabric of reality at soft spots and create more vortices. After one such incident at a theater, Peter and Olivia (Anna Torv), now married, along with Astrid (Jasika Nicole) and Ella (Emily Meade), Olivia's niece and now a rookie Fringe agent, find an unactivated container that they believe the End of Dayers used to trigger the breach. Fringe is unable to determine how the container works, and Peter convinces Broyles (Lance Reddick), now a senator, to allow him to release his father Walter (Noble), currently in maximum security prison as punishment for activating the doomsday device, to help identify its workings.
After tearfully reuniting with his son and new daughter-in-law, Walter discovers the device uses a unique radioactive signature that they can track. The strongest source points to a used campground, where Peter discovers a key. He recognizes the key as from Walter's old home near Reiden Lake and travels there alone, and finds his biological father, Walternate, present. Walternate admits to being behind the End of Dayers group, as his revenge for Peter activating the doomsday device and destroying the parallel world that was his home. Walternate promises that Peter will face the same pain and suffering he has faced since crossing to the prime universe on a mission of mercy, one piece at a time. Peter realizes that Walternate is implying a threat to Olivia, and finds that Walternate was speaking to him remotely through a holographic simulation. In Central Park, where Moreau has set off another breach to expose an existing wormhole, Olivia is helping to cordon off the breach when Walternate approaches and shoots her. Peter and the rest of Fringe division struggle with her death at her funeral.
Walter continues to study the Central Park wormhole and discovers that it links to the past, approximately 250 million years ago. He comes to realize a temporal paradox (a bootstrap paradox): he will have sent the doomsday device piece by piece into the past, effectively becoming the "First People" mythos, and convinces Peter that they can influence Peter in the past by having him experience the end of days himself and make a different decision when he enters the machine.
