Amber 31422

Olivia is still trapped in the parallel universe, under Walternate's (a doppelgänger of Walter Bishop) conditioning to believe she is her doppelgänger from Over There and part of its Fringe team. Throughout the episode, she willingly participates in Walternate's tests in a sensory-deprivation tank located on Liberty Island to stimulate her Cortexiphan abilities. One test is successful, as she temporarily finds herself in a gift shop on Liberty Island in the prime universe. Meanwhile, hallucinations of FBI consultant and colleague Peter continue to bother Olivia.

The Fringe team is alerted to an incident at a quarantine site, where the amber encasing the site has been cut into and a body has been removed. They identify the missing body as Joshua Rose, a former bank robber. Joshua had previously caught Fringe Division's attention as he used a molecular destabilization device to break into banks, triggering quarantine-level events. Colonel Broyles is privately cautioned by Walternate that those trapped in amber are still alive, a fact he does not want to be made public for fear of an outcry. Broyles relays this to his team, requesting they find Rose and bring him in as quickly as possible.

At Joshua's apartment, they discover he has a twin brother Matthew and equipment used for a negative matter ring. Their investigation is cut short as they are forced to evacuate from a rigged bomb which destroys the apartment as they flee. Lee and Francis were unable to hear the bomb, but Olivia could, possibly indicating that she retains the enhanced hearing demonstrated in "Night of Desirable Objects." They travel to Matthew's home in the suburbs, meeting the brother, his wife, and their children. Matthew professes to no knowledge of the location of his brother. Olivia is suspicious of Matthew's behavior but does not explore further. Olivia's suspicion is shown to be correct as Matthew is revealed to have been the one trapped in the amber, having tried to come warn his brother about the quarantine. Joshua, having posed as Matthew for the last few years, was the one that freed him and spoke to Fringe. The brothers switch places again when Olivia requests a more detailed identity check from Matthew, which he passes successfully.

Believing Joshua will attempt another break-in but will avoid putting innocents in danger, Olivia has Fringe Division statistician Astrid identify three remotely located banks and decides to investigate them. Olivia finds the bank that Joshua has targeted and discovers his device in a subway tunnel, but he knocks her out before she can investigate further. As he energizes the molecular destabilizer, Fringe Division detects the event and converges on the bank. Matthew eventually finds Joshua, again trying to warn him off, but quickly realizes Joshua has purposely entered the bank to be trapped in the amber. Joshua believes this to be the only way to force the Fringe team to end their investigation. Matthew escapes the quarantine while Fringe agents Charlie and Lincoln rescue Olivia in time before the amber sets in. Olivia returns to Matthew the next day and confirms the case is closed, but not before collecting a skin sample that, should she ever need it, conclusively proves that it was Matthew in the amber before.

As the episode ends, Olivia's hallucination of Peter points out to her that there is a way to tell if she is from the prime universe: by confirming her memories of her niece Ella, who did not survive birth in the parallel universe. During Olivia's final test in the tank, she is again able to cross over to the gift shop in the prime universe. She is able to recall Ella's phone number and calls her, but is brought back to the parallel universe shortly after Ella answers. As she is removed from the tank, she lies, telling Walternate the test did not work.

Co-executive producer Josh Singer and story editor Ethan Gross co-wrote the episode, while David Straiton served as the director.^[1] The third season spent its time alternating between the prime and parallel universes, and "Amber 31422" was set in the latter.^[2][3]

"Amber 31422" was the first project guest actors and brothers Shawn Ashmore and Aaron Ashmore had worked on together in fifteen years. Shawn said in an interview that "it’s usually because the stuff that came along is kind of hokey, but I think the quality of Fringe is really high and the episode is done well and our characters are intelligent. We’re going to have some fun."^[4] Holly Dignard guest starred as Danielle Rose, while recurring guest actors Amy Madigan and Ryan McDonald returned as Marilyn Dunham and Brandon Fayette, respectively.^[5] Seth Gabel and former series regular Kirk Acevedo reprised their characters Lincoln Lee and Charlie Francis, Fringe Division agents from the Other Side.^[6][7]

The episode was scheduled to air three weeks after the previous episode, as the Major League Baseball playoffs were underway until November 11 at the latest,^[8] though the lack of a sixth and seventh game at the World Series allowed the episode to air a week earlier, on November 4.^[9][10] As with other Fringe episodes,^[11][12] Fox released a science lesson plan in collaboration with Science Olympiad for grade school children, focusing on the science seen in "Amber 31422", with the intention of having "students learn about the process of fossilization and identification of species from incomplete information."^[13]

In the parallel universe, Lincoln Lee mentions that it was Cary Grant, and not Humphrey Bogart, who starred in The Maltese Falcon.^[2][14] After Olivia arrives late to a crime scene, Lincoln chides her for driving on the "Nixon Parkway," a reference to former president Richard Nixon. The tank Walternate uses to submerge Olivia has been noted by some critics to closely resemble a similar device in the 1980 science fiction film Altered States, which also starred Fringe actress Blair Brown.^[15] Walternate tells Broyles he first began the amber protocol on October 17, 1989, which was the same day as the 1989 Loma Prieta earthquake in our side's San Francisco Bay region.^[14]