“Through the Looking Glass and What Walter Found There” is episode six of season five of Fringe.
Walter has got another tape from the amber and Walter on the tape is heading on a journey to show how to get the next piece of the plan.
Peter is watching a hologram of Etta when Olivia turns up. He didn’t come home and wasn’t answering. Peter says he just needed to see her. Olivia had thought to come too. And what’s Peter to include her when she feels like this. She notices the bandage on Peter’s neck where he implanted the Observer tech in the previous episode, “An Origin Story”. He lies about what it is.
Walter is watching the video of him arriving at a building, making notes. He heads to Boston and is spotted by cameras as a fugitive. The building is now badly damaged, and a woman with a cybernetic implant for an eye, seen on the tape, speaks to him. Walter climbs some damaged stairs to a mirrored apartment, follows a pattern of walking and steps out of reality. Into a different place that seems odd.
Astrid arrives at the lab and is looking for Walter when Peter and Olivia arrive. Astrid thinks Walter got the tape from the amber and left. They watch the tape; Walter says he has created a unique hiding place that the Observers can’t detect. A pocket universe in the space between the universes, one where the usual laws of physics don’t apply. On the tape, Walter arrives at the mirrored apartment and hands the camera to someone called Donald. Possibly the Donald mentioned in “The Recordist”. There’s a sequence marked on the floor showing how to enter the pocket universe, then the tape ends.
Walter is in the pocket universe and ends up being held at screwdriver point by someone called Cecil. Cecil wants to get out. He was in one of the building’s apartments and the resistance must have been in the area because the invaders hit the whole block with light bombs. Cecil awoke here and has been there for five days. He has no food but has some water. Walter wants to see it.
The water is condensation and Walter thinks there’s something behind the wall, perhaps a refrigeration unit. Cecil says there’s nothing on the other side. Walter thinks there is. He’s been here before; he just can’t remember it.
The other three also turn up at the apartment and Peter and Olivia make their way into the pocket realm. The Observers are also incoming. And something unexpected was hidden in the pocket universe.