Olivia uncovers a dangerous force that may be connected to Walter's past experiments with the drug Cortexiphan. Their investigation forces Walter to leave the lab for the first time in years as he and Olivia head to Massive Dynamic in New York to examine old case files. Walter struggles with life outside the lab as he comes face-to-face with the demons of his past.
original airdate- October 14,2011 rating-3.1 million
songs Theme song by JJ Abrams