One Night in October
Fringe Season 4 Episode 2 (09/30/11)
The two universes must work together to stop a serial killer who steals people's memories.
The Olivia's work side by side in identical dress, but that's as far as their similarities reach.
Lincoln is an apt pupil in the Fringe division and eagerly learns as much as he can.
Walter is struggling to keep his sanity as Peter tries desperately to reach him.