In Boston, Peter siphons gas out of a car and then enters a store with what I guess could be called antiques. The store is run by a Jamaican man with dreadlocks, but before he can say that he is looking for a new chain for Henrietta, Windmark hands him the chain. Windmark says that it will look good on the young woman. This freaks Peter, so he starts to think about baseball. The observer tells Peter that he is upset and does not like to be read. Peter hands over a twenty and rushes out of the store but he observer follows and tells the guards outside to detain Peter. To escape Peter climbs down a manhole and though he pulls out his gun to protect himself, the guards do not follow and instead drop a bomb. Peter wakes up on the ground after climbing out of a storm drain.
Astrid and Walter have released another tape from the amber but Walter is not impressed with the pace at which they are working. Peter returns to the lab and Olivia is concerned that he is hurt. Peter says that he is fine and explains about the run in with the observer. He tells Henrietta that the observer got an image of her from his brain but figures that since she has already been exposed that it's fine. Peter is concerned that they will never beat the observers but Etta reassures him that he did the right thing instinctively but he has to build a labyrinth of planned thoughts. Peter believes that it is impossible but Etta assures him that she has taught others, but it just takes a really longtime. Peter hands her the new necklace and she hugs him.
The observer is still in the store when in walks Broyles. I was starting to wonder if he was ever going to appear this season. The observer is holding up a necklace and asks Broyles why Peter would put himself at risk to buy this. The observer points out that the fugitives are confidant enough to walk freely and he believes that the resistance is protecting them. In what is a clearly threat, the observer informs Broyles that a man in his group failed his security test last week. When Broyels asks why he wasn't informed about the security fail, the observer says, "I could ask you the same question." Broyles responds "I didn't know about it," to which the observer says, "that is my point."
Back at the lab, they are watching the tape but it is so blurry that it is hard to make out. Astrid pulls the tape out and says that it's ripped but it's not a concern because Walter says that the item they need is hidden in the wall at Newarks Penn station. Etta says that every major access to Manhattan has an observer check point. Walter replies that he needs to get to the rolling cabinet in the amber, but Astrid thinks that this is ridiculous because the cabinet only holds his easy bake oven. Walter says what's important is not the cabinet, but what is under the cabinet. Underneath the cabinet is a set of stairs but before the team goes down Walter gives them Mentholatum to deal with the smell.
When they get there, they discover that Walter has a storage of all of the fringe events that they have ever worked on. Walter believes that they need to create a Fringe event, in order to have a distraction. It seems that he kept them all because he has a healthy distrust of the government. Walter says that he will have to go through everything to see what is still viable but before doing do so, he eats the most disgusting doughnut ever.
The man who failed the security test is being questioned. The observer pulls up a copy of the tape. The lie the resistance fighter was caught on was about the weather, the day he supposedly graduated from the academy. He tries to lie his way out of it and the observer starts to read his thoughts, as the man struggles. The observer asks about Peter Bishop and unable to fight anymore, the man thinks about someone called the Dove but fortunately, he doesn't know the Dove's real name. As the questioning goes on, Broyles watches the video feed. The observer then enters Broyles office and says that the man they were questioning is a low level operative. The observer picks up the lab from Broyles mind and points out that he had a relationship with the fugitives. The observer is clearly trying to read Broyles but all Broyles says is that he knew them a long time ago. The observer says that the fugitives are in the lab and leaves to make his report and Broyles takes his hand off his gun.
In the lab, it looks like Walter has found a delivery system for whatever plan he is hatching. On the a computer, Olivia notices that there are even more loyalists at the subway station. Etta starts playing with the bullet on her new necklace. It turns out that this is a bullet that Olivia saved, which Etta took from their old apartment when she was 13 in order to feel closer to her mother. Etta offers the necklace back to Olivia but Olivia says that she wants Etta to keep it. Olivia tells Etta that Peter used to call the bullet, "the bullet that saved the world." Etta then gets a call that the lab has been compromised.
Broyles is riding in an elevator with an observer. Olivia and Etta tell Walter and Peter that the observers know that they are in the lab. Walter is distraught because without the tapes, they cannot rid the world of the invaders. Olivia suggests that they re-amber the lab. By the time the loyalists break into the lab, there is nothing to see.
The observer is upset because he now believes that the prisoner was deceptive. He pulls up a hologram of Etta and says that somehow she hid her thoughts from them and wonders if others can as well. Broyles who is sitting across from him does not say a word.
At the checkpoint, Walter pulls up and asks for directions. Walter is asked for his authorization and when he does not reply, they electrocute him and ask again. They ask again for Walter's authorization and this time, he turns around with a gas mask on and sprays something at them. When the guards fall to the ground, Peter and Walter get out of the car and Olivia and Etta drive around back.
Peter and Walter head into the station and they pull a tube out of a vent. Outside, Olivia watches anxiously and then she and Etta put on gas masks. In the subway, Peter is forced to shoot two loyalists to escape. Outside the station, Olivia is firing the Fringe weapon, which seals the eyes, nose and mouth of the people that the gas touches.
In his office, Broyles is packing his bag and he stops to look at a picture of Olivia and Peter together. In the meantime, the Fringe crew has found someplace to park to look at what they retrieved. It turns out that it's a scroll with a form of physics that Walter has never seen. He cannot even begin to make sense of it. Olivia suggests that they head back to the lab but Etta says to wait because someone wants to see them. Broyles pulls up and Olivia greets him with a hug. Broyles, Walter and Peter shake hands. It really upset me that he didn't even ask how Astrid is doing. He has to know that she has been freed but somehow once again, Astrid has been deemed unimportant. Broyles says that he asked Etta not to tell them in case they were read. He says that he tried not to see them but just had to now. Broyles also tells them how he came to meet Etta and have her transferred into his section with the intention to look after her, but Etta recruited him into the resistance.
At the station, the observers are looking over their dead and call the weapon the Fringe team used barbaric. A loyalist approaches Windmark to say that one of their men died holding a tracking device. As the Fringe crew pack up, an observer shows up. Broyles shoots the observer and tells them to run. The team heads out on foot and Broyles leaves in his car, just before Windmark and another observer arrives. Windmark ominously points in the direction the Fringe team ran in.
The team runs into a factory but the Observers quickly follow. Loyalists immediately surround the factory outside. Inside, a firefight begins and Etta and Walter get separated from Olivia and Peter. Peter suggests that he and Olivia go over the roof and promise to go back for Etta. Etta is walking through the factory alone, when she is caught by Windmark. In the meantime, Peter and Olivia find Walter's hiding space.
Windmark starts to read Etta's thoughts and he sees her as a little girl running to Peter. He realises that Peter bought the necklace for her for love. Etta grabs a knife to try and stab him but he catches her hand and forces her to drop the knife. Windmark takes a step back and shoots Etta and walks away. Etta lies on the ground clutching her necklace. At first, Peter and Olivia tell her that she is going to be okay but they have to move her. Etta tells them that they have to leave her there and that they won't make it out with her. Etta has started a bomb and tells her parents that they have to leave. Olivia tells says to Etta, "I love you so much," and then takes the necklace out of her hand. Peter hugs her and starts to cry and in the background tears stream down Walter's face.I don't know about you but I a not going to miss Etta one little bit. They introduced her and expected us to bond with the character based in the fact that she was Olivia and Peter's daughter but that was not enough for me.
Outside, a loyalist tells Windmark that they are sweeping buildings 2 and 3 but there are no signs of the Fringe team. Windmark realises that they would go back for Etta because they love her. When they find Etta, she is alone and Windmark realises that the necklace is gone and looks down and sees the bomb. He shifts out of the building just before it goes off. Peter, Olivia, and Walter watched the blast from a distance and Walter says, "she's gone son, we have to go." Olivia walks on but Peter does not move, so Walter repeats, "she's gone son," before leaving and Peter continues to stand there.