Peter, in the grip of mourning Henrietta's death, resorts to extreme measures in order to gain powers that will allow him to surpass those that the Observers possess and hopefully, and eventually, find a means to defeat them.
As Walter fears Peter and Olivia losing themselves over Henriett's death, Peter heads down a road of revenge, brutally interrogating a captured Observer to understand the assemblage of a future tech cube used in transporting cargo through time.
Peter and Olivia are mourning the death of Etta but Peter contacts Anil and learns the The Observers are bringing equipment to change the atmosphere. Peter decides to bomb the wormhole to the future used by The Observers. Anil discloses that the resistance have captured an Observer and one device used to open the wormhole. However they do not know how to assemble the parts of the equipment. Peter uses his experience to judge The Observer's reaction and assemble the device. However it does not work properly and the emotionless Observer tells that he lured Peter. What will be Peter's attitude?
- Peter goes through Etta's things as Olivia sleeps. He notices how much his late daughter looked like his wife. He finds a secret compartment that reveals a cache of weapons and explosives.
"That's my girl," he says as he arms up. Olivia wakes up. "Why would we get her back just to lose her again?"
Later, Olivia looks at a photo of Etta as a child with the woman who raised her.
Manhattan Shivers of static electricity appear on buildings and in the street. Observers roll up with Loyalists and start to unload crates. One takes out a cube-shaped machine and turns it on. A portal opens and three large pallets slowly move through and appear in front of them, scorching the earth around them.
Back at Etta's, they prepare to leave. Walter wants to take her perfume to remember her by. Astrid calls from the lab to report she's run into a fire hazard, Walter left a propane tank in the way of the Beta cassette before they ambered the lab. It'll be a few days before she can get to the next cassette.
Anil calls Etta's phone, wanting to meet.
Anil meets Olivia, Walter and Peter at the scorched earth spot in Manhattan. They think it's from a wormhole from the future and the parts are to build the air degredation system. The Resistance wants to destroy the next shipment when it comes, but they can't read the Observer's language. Anil gives Olivia a book with characters in it and shows her video of the Observer they captured and took it from. They have the cube. Peter wants to try to use the cube to destroy the entire wormhole. Walter thinks it's too risky.
"Before you go on a journey of revenge, dig two graves," Anil warns Peter. But Peter's not worried about himself, he just wants to defeat the Observers.
Later, Peter works on the cube but it zaps him as he takes it apart. Back at the lab, Astrid puts the Observer's notebook through a decryption program. Olivia is trying to keep distracted from thinking about Etta. Astrid realizes each of their symbols could stand for more than one thing, she wants to run multiple decryption programs at once and needs more computing power.
Walter checks on Peter, who reports the cube is packing a ton of power. Walter thinks he knows how to destroy the shipping corridor, but it's very dangerous. Walter shows Peter a model of the future to explain his idea to turn the wormhole into a blackhole that is closed on their end and will back up in the future. They'd have to throw in an anti-matter baton, but they'd have to get to the wormhole with the cube before the Observers. Peter wants to force the Observer to help them.
As Peter packs up, Olivia tries to get Peter to slow down, reminding him they also have Walter's plan. "But what do we have? Pieces we don't know how to put together, a scroll with physics we can't decipher, a thought unifer that doesn't work and a box of rocks from a mine. That's what our daughter died for so far," Peter says.
Olivia tells him she's afraid, but he assures her he can do this. He wants everyone to know Etta helped save the world. Walter listens to their conversation. Peter leaves the lab and joins Anil with the unconscious Observer. Anil explains the Observer's abilities are aided by tech. He wakes the Observer up and leaves him with Peter.
Peter takes out the cube, explaining to the Observer that he's going to help him figure out how to use it. The Observer doesn't understand why Peter would think can get him to cooperate when the others couldn't. "You don't even know what you don't know," the Observer says. "We'll see," says Peter.
Peter sets a tiny camera up very close to the Observer's eye and studies his micro reactions as he picks up pieces of the cube and puts them together. The Observer compares humans to ants. "You think the black over your head is dark skies, but it is really our shoe," he says. Peter continues putting the cube together, the pieces fitting perfectly in the right order.
Walter comes to Olivia in the lab with tape of one of Etta's birthdays. "It will be incredibly difficult for you to watch, but I believe it's important for you and Peter to see it," he says. Walter tells her what he overheard and knows she meant she was afraid for her relationship with Peter. Walter tells them they have to face their pain together. "I have experience with this kind of pain, and you can't escape it by building walls around your heart. Or by breaking the universe, or by vengeance," Walter says. "You lost each other once, but you have another chance." Olivia refuses to watch the tape.
Astrid announces they decoded the book, it is a shipping manifest and the next shipment is this afternoon.
Back with the Observer, Peter knows if he attaches the next piece incorrectly, they'll be obliterated. He watches the Observer's reactions as he holds it over the four placement options. Although the Observer says he doesn't care if he dies, Peter says he still has human-based subconscious reactions that he can't control. He watches the Observer's pupils as they expand and contract and puts the piece in the right place. He continues. Olivia calls to tell him where the corridor will be opening. Peter puts the last piece in the cube and it turns on.
At the location, static electricity is already appearing and Observers are setting up a cube. Anil sets theirs up in the road. Peter aims the anti-matter baton from building. The Observers notice the corridor open across the street from them and realize something is wrong.
Before Peter can fire from his perch, and Observer appears behind him and kicks him across the room. He kicks Olivia over as she takes aim. The Observer stands over Peter and raises his shoe over him, about the crush the ant. But Olivia stands up behind him with the gun and shoots the Observer.
Peter aims the anti-matter baton into the corridor and hits it. It closes, its contents being sucked back in. They get in the van and are driving off in a celebratory mood when Anil checks the review mirror. They stop and look down the street. Another shipment is arriving through another corridor.
Peter calls Walter for an explanation, but he's stumped. Peter stalks off "to get answers." Olivia looks at the alley where she's standing and sees signs with Etta's face on them saying "Resist."
Peter charges in on the captive Observer and holds plastic over his face. When he asks why it didn't work, the Observer again tells him he doesn't even know what he doesn't know. And that Anil was right about digging two graves before a journey of revenge.
The Observer explains he was watching a fly on the wall and that made his pupil dilate. "You ascribed meaning to something that was not there," he says. He says Peter put the device together from his experience as an engineer and just needed his reactions to build confidence. Whether they caused Etta's death is irrelevant, the Observer says, because she was here and now she is not. "You are nothing but tech, I would be ten times what you are if I had that tech in my head," Peter says, before he knocks the Observer out.
Back in the lab, Olivia contemplates the birthday tape. She puts it in.
Meanwhile, Peter picks up surgical tools and slices the Observer's neck open, comparing the pain to the pain a father feels when he loses a child. Peter removes a small processor as the Observer dies.
Olivia watches the tape of her with Peter and very young Etta. They're all very happy.
Peter slices into the back of his neck and inserts the processor, which leaps to his skin and climbs up to his brain, giving him the mother of all headaches. Olivia calls in tears as the tape plays, asking him to come home. "Etta would want us to be together, she would want us to survive this. I love you," she says.
Peter says he loves her but has to get off the phone as something strong comes over him.