Following an unexplained attack involving disfigured humans, the Fringe team visits Edina City, a small town in upstate New York, to uncover leads surrounding the bizarre case. When it's determined that these disfigured people have managed to hide for a while and theylll do just about anything to keep it that way, the investigation takes an unexpected turn.
Synopsis provided by the Fandom Wiki, Fringepedia, and Wikipedia.
This episode's glyphs spell:
Humans and other creatures living within the limits of Edina had genetic mutations that were hidden to an observer's eyes by a form of electromagnetic camouflage.
The Observer can be seen when Sheriff Velchik is briefing the townspeople of Edina.
Colorful butterfly drawings hung up at Dunwich Mental Hospital in 'Grey Matters' foreshadow Walter's discovery of Edina's permutation secret in 'Johari Window' when he captured a butterfly for Astrid that later seemed to change its appearance.
The storage box marked "Magellan Files" near Walter's library hiding place in 'Johari Window' foreshadows Walter's recollection of the Magellan's travels and the potential for decimation/extinction exploration can bring in 'What Lies Below'.
Walter was struggling with whether or not to tell Peter about his true origins from "Peter".
As Olivia started remembering things from the original timeline in "Welcome to Westfield" she mentioned the case in Edina from "Johari Window".