The latest episode of Fringe, "Letters of Transit", proved one of the most complex in the show's history. It takes place in 2036, some 15 years after the Observers have taken over the world. Much like a fascist organization, they've established an order with little freedom. They take what they want, kill who they want and rule with cruelty.
There is, however, a resistance group of humans working within what is left of the FBI. One such agent is Etta, a lovely blonde with haunting eyes. Another is Simon, a handsome scientist who holds on to hope. His parents got killed during the occupation by the Observers and he's vowed not to quit until they are gone.
As the episode begins, a friend of Etta's has gotten hold of a person trapped in amber. The audience quickly learns it is Walter Bishop. She's told that the rest of his team got trapped too, but he's shot before he tells her where.
Excited, she takes Bishop's body to Simon and they find a way to get him out. But when they ask him where the rest of his team is, he can't remember. His brain's neuropathways have degraded.
Trying to find a way to fix him, they visit an old friend, Nina Sharp. She tells them a piece of Walter's brain remains housed in the old Massive Dynamics building. If Simon can insert it back into Bishop, it might help repair the neuropathways.
There's one problem though. Natives aren't allowed in the city without authorization. Simon and Etta have to fake papers to gain access. Along the way, they get stopped by the Observers élite guard. But Simon manages to talk his way out of the situation.
The threesome make it to the city and find the needed item. However, they trip an alarm wire on their way in, alerting what's left of Agent Broyles who has become an Observer lackey. Still, they have just enough time to do the job they came to do.
Walter's brain heals itself just minutes before the Observer army arrives. He out smarts them though, giving the threesome time to set a trap and escape. Then he takes Etta and Simon to the place where the remaining Fringe members stay in amber.
Using the same device they used to get Walter out of the casing, they remove Astrid. However, the device breaks before they can finish getting everyone else out. They have time for just one more person. Eyes fall on William Bell.
Using the weight of his own body to push one of the team member's out, Simon becomes cased in amber himself. That's what the Observer's army finds when they arrive. That and a strange device the Observer can't make out, at least until it's too late. As Etta, Astrid and Walter escape, the Massive Dynamics building blows up.
Astrid asks Walter why he left William Bell in the amber. Walter responds, "you know what he did to Olivia." Then the scene cuts to Etta who fingers her necklace. The camera draws back to show it is a bullet. It's the same one Olivia wore like a lucky charm around her neck.
Peter Bishop walks up to Etta. She looks deep into his eyes and asks if he knows her. At first, he says he can't possibly, having been in amber for 20 years. However, as he looks into her eyes, a spark of recognition grows. He realizes it his and Olivia's daughter—Henrietta. The episode closes as father and daughter embrace.