Fringe/Recap/S03 E05

Season 3, Episode 5:

Amber 31422
In the alternate universe, a team of thieves carve someone out of a block of amber that's been used to quarantine a bank. The man being rescued -- the twin brother of one of the thieves -- is successfully revived, but when the amber begins to reform, one of the thieves is caught and trapped. Fringe Division investigates and realises that the man who was rescued is Joshua Rose, a bank robber whose phase-shifting technology caused breaches and ultimately led to him being accidentally caught in quarantine during one of his jobs. The team don't understand why someone would be taken out of amber, until Walternate (the inventor of amber) reveals to Broyles that people encased in amber aren't dead: they're in suspended animation, contrary to what the population believes. Walternate demands that Joshua be caught in order to protect this secret.

When Olivia and Lincoln interview Joshua's brother Matthew, who has a wife and children, Olivia begins to suspect what really happened: Matthew Rose was caught in the amber, Joshua has been pretending to be Matthew during the intervening years in order to provide for Matthew's family, and now he's finally saved Matthew. When Joshua realises that Fringe Division is figuring it out, he comes up with a plan to rob a new bank, believing he can solve everything. Matthew and Olivia both realise at the same time and follow Joshua to the bank: Joshua knocks Olivia out just before Matthew arrives. Matthew doesn't understand how robbing another bank will help, but Joshua explains that it's not about money: by using his phase-shifting technology, he's already triggered a quarantine protocol that will trap him in amber, satisfying Fringe Division (who now have Joshua "back" in amber) and giving Matthew a chance to live with his family. Lincoln and Scarlie pull Olivia out of the quarantine zone before the amber is released, trapping Joshua. Later, Olivia visits Matthew, having figured out about the switch, but she decides not to inform Fringe Division.

Meanwhile, Walternate wants to start using Olivia for experiments in travelling back and forth between the universes. During the first experiment, which involves going in a sensory depravation tank in the DOD labs, Olivia is able to briefly travel to the prime universe, arriving in a gift shop and returning extremely quickly. Walternate and Brandon are able to identify a nootropic -- cortexiphan -- operating in her brain during the trip. At the end of the episode, Peter appears to Olivia again, telling her things about the prime universe that "Fauxlivia" couldn't possibly know, such as the fact that it's Ella's birthday and that the twin towers were destroyed. Olivia volunteers to go back in the tank and travels to the prime universe: within the minutes that she's able to stay, she confirms that the twin towers have fallen and is able to call Ella and wish her a happy birthday. When Walternate and Brandon pull her out of the tank in the alternate universe, she claims that it didn't work.