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Fringe, season 3 episode 19 «Lysergic Acid Diethylamide»: air date April 15, 2011. Episode overview, season trailer and the cast of Fringe.
Back "over here", Walter and Peter embark on a desperate mission inside Olivia's subconscious mind, in an attempt to remove William Bell's consciousness from Olivia's body before her soul is lost forever. Meanwhile, Astrid takes care of Broyles when he's accidentally exposed to LSD in Walter's lab.