German agents question Olivia about her "relationship" with David Robert Jones, an escaped prisoner questioned months earlier now living in the U.S. The Fringe Division investigates a threatening case where victims die faceless from their orifices suddenly sealing.

When all of the groom's relatives asphyxiate at a wedding, the Fringe division investigates and quickly ascertain that a human agency is responsible. Walter realizes that the formula for the toxin was based on research conducted by his father, Robert Bischoff, and that the killer isn't stopping with a single test of his lethal concoction.

Back “over here,” the Fringe Division investigates a bizarre phenomenon when 15 people up and down the Eastern Seaboard, all suffer retrograde amnesia from listening to their shortwave radios on the same frequency. Much to Walter’s dismay, Peter presses on with piecing together the mass destruction device. Just as alternate Olivia and Peter’s chemistry deepens, the anticipation of Olivia’s return escalates.

The Fringe team faces a case that appears familiar to Peter. Strangely, it takes place in this timeline.

The Fringe team - preserved in amber for 20 years - is now a rebel resistance team fighting for freedom. Peter, reunited with his now adult daughter, Etta, sets out to find out what happened to his wife and Etta's mom - Olivia - as they start their mission to save the world from the Observers.