“Letters of Transit” is episode nineteen of season four of Fringe.
This episode opens with a text introduction, about how the Observers came from the future and at first only watched, but in 2015 stopped watching and took control. The original Fringe team was defeated and Fringe Division was allowed to continue to police the natives. Resistance was quickly overcome. Or so they thought.
Boston, 2036, and a woman, called an agent, enters some kind of club filled with Observers and others. An Observer grabs a woman and a man objects. This escalates and another Observer looks at the man until his ears start to bleed. Then the agent knocks the man down. As a native, he’s her jurisdiction. The Observer stares at her and says she’s always exactly what she seems.
The agent takes the woman and man outside; she tells the woman to go home. The man, Rick, said he had to annoy the Observer so he’d try to wipe Rick, not read him. And if the Observers find out that she can avoid being probed, they’ll kill her. He’s got something for her in a van. There were two others, younger, a man and a woman, where he found this one. Before he can say where, someone kills him. She drives off in the van. What he found was an ambered Walter.
At Fringe Division, the agent speaks to another one, Simon Foster, who calls her Etta. They head outside and she tells him Rick is dead. Etta mentions the missing Fringe team and Simon is telling her they died 20 years ago. Etta explains they didn’t; she’s got one in amber. Walter has the amber device in his hand; they need to get him out to find the rest.
An Observer heads to see Broyles to tell him native on native killing cannot be allowed. Either Broyles sorts it, or the Observer will be put in charge of the case.
Etta and Simon are working on the amber. It only turns to gas momentarily. Etta goes to get a device for Simon. This is a crowd control device that can be used to blast things across the room. In the moment when the amber is a gas, Walter is blasted out of it. Foster introduces himself to Walter.
Walter was apparently working on a device his team discovered to get rid of Observers. However, whilst they’re talking to him, he forgets who they are. Simon scans Walter; his neural pathways have degraded. Brain damage. Simon doesn’t know how to fix it.
Etta heads to the Ministry of Science in Brooklyn to see Nina Sharp. They talk about something, but that was a ploy for when they are outside. Nina asks if there’s any progress with Walter’s device. Etta indicates Walter. Nina can’t fix Walter, but at the old Massive Dynamic, there’s some of Walter’s brain tissue in a vault. It might be possible to use it to make Walter’s brain heal itself. However, it’s in the city. Which is full of Observers.
Getting Walter in his current condition to the city is difficult; when they’re stopped by a guard, he references both The Prisoner and Star Wars. Things are not wrapped up in this episode; it seems this is one of several. This is also the first time that the Observers have really been portrayed as a dangerous threat.