We start where we left in Season 3. Where did Peter go? When he plans to come back? The whole reason this war between worlds started was because Walter crossed over to save the not-dead young Peter and then decided to keep him as a friend or so. Years later, Walter is still trying to make up for his moment of weakness and Walternate who killed Olivia is still trying to get his revenge. And now we know that the main observer of the show, Peter never existed? Why the need for that long bridge at Liberty Island? Walter is getting crazier each moment. Olivia has a hole in her life that she does not like to explain. The cooperation plans are a bit hard at the Liberty Island.

Olivia and Fauxlivia are exchanging all Fringe Division files and making it clear that they really don’t like each other and falling into hatred with each other resulting in the war. They must not have done that, in order to get the job done they must have mutually cooperated. Yet there is no trust between the two and no love at all. As Peter is gone so it is assumed that there is no Baby Henry, and mostly the people don’t like to see any more of that stuff, which may have made the relationship between Olivia and Faux even more intense.

As we move on to the scene of Lincoln and his partner, Robert Danzig, chase a bad through the streets. Lincoln finally catches the guy and founds that he lost his partner as well in the run. So he decides to look for his partner but when he goes looking for his partner, he finds a creepy transparent dude leaning over Danzig’s dead transparent body. Later on Fringe Division is called in to check the body. It is interesting to note that Walter, in this absence of Peter in the world, does not go to the crime scenes. He stays in the lab all the time. Olivia is still keeping an eye on him, they don’t know each other at the start but slowly they get to know each other and begin to fall on each other. The Observers in the show are very strange things and they keep on doing the work they know they don’t find peter anywhere. They recognize the changes in the main players because Peter is not in the game. Walter is actually seeing images of Peter as he does not know who the person is. The Observers need to take action to ensure that no one learns that the boy never grew to be a man. This statement means that Walter never crossed over to kidnap the other Peter. Now why is there war without the kidnapping-Peter catalyst? Some assume that maybe Walter did cross over to get Peter and he didn’t survived. Now it comes to the observers to erase the images and flashes of the Peter coming to Walter’s mind. They must make sure that no one gets a sight of what they are doing and what they have done in the town recently.

Now Lincoln learns that there have been dozens of victims of this transparent dead body which he does not recognize. It is just like they have been unknown to each other. Suddenly Lincoln learns that Danzig had Cohn’s Disease. This puts Walter onto the discovery that all the victims had conditions that resulted in an excess of metals in their body system which may had iron, zinc, etc to cover up the story. Now this discovery includes the theory that the bad-die works with the transit system in some way of unnatural criteria. Finally they get the killer with another transparent body no one recognizes and the questions are coming from here and there and no one is there to answer them and the mystery continues.

Meanwhile, Walter does an autopsy and finds some disturbing evidence that these creatures are actually human shape shifters may have come from any other planet. In the past, those shape shifters had always been under the control of Walter, of course Walter does not remember that, so he is disturbed. Olivia decides it’s time to introduce Lincoln to the bridge between worlds to confront Fauxlivia with the evidence that Walter had found. Fauxlivia is comfortable with the idea of getting along with Walter. September has made a mess of many things and his quick healing didn’t work at all. He had been ordered by the head of the Observer’s to take care of it all, but when it came down to it; September couldn’t wipe Peter’s flashes and images completely from Walter’s psyche. He’s now expected to be going to get in trouble.