Fringe: Season 3, Episode 5

3 - 5: Amber 31422

In the parallel universe, a twin frees his brother (guest stars Shawn and Aaron Ashmore) from amber. Walternate reveals that those who are trapped in amber aren't dead, but in suspended animation and those who are released will compromise its structural integrity. However, if someone was to reveal this, it could be damaging, so the Fringe Department is tasked to capture those responsible. Throughout the episode, it is revealed that one of the twins is a serial bank robber, and when the innocent brother was ambered, he posed as him. In the end, the bank robbing twin gets ambered. Meanwhile, Walternate experiments on Olivia by taking her to a sensory deprivation tank . Olivia succeeds in traversing universes temporarily. In the end, a hallucination of Peter convinces her who she really is.