At the Elias Cyrogenics company in Medford, Massachusetts, two deliverymen are preparing a shipment of bodies. As the truck begins to pull out, a man pulls up and asks for directions. The security guards tell him he's trespassing and he draw as a gun and shoots at them. As the deliverymen duck for cover, one of them draws a gun and shoots his partner. He goes to help his partner, the first hijacker, but a security guard shoots him repeatedly. The hijacker escapes with the truck while the deliveryman finally goes down, bleeding silver blood and revealing he's a shapeshifter.
At Harvard, Walter has Astrid cut up flatworms for a concoction he's making. When Olivia comes in, Walter explains that he believes he can make a formula consisting of flatworm brains to help her regain her memories. Peter doesn't believe it will work but Olivia ignores him and drinks the formula. Nothing immediately happens, and they get a call to report to Elias Cyrogenics. Broyles informs them that it's the third in a series of thefts of bodies from cryogenic companies. While Walter takes a sample of the shapeshifter's mercury blood, Olivia sees Peter approaching and gets a memory of William Bell walking toward her the same way. Meanwhile, the shapeshifter disguised as Charlie arrives and asks Walter what he's doing. Walter notices that he looks ill and offers some marijuana, and then finds the dead shapeshifter's alteration device.
The shapeshifter hijacker is in the woods removing decapitated heads from the stolen cryogenic chambers. The Charlie shapeshifter arrives and warns that he was careless to let one of their own fall into enemy hands. The hijacker notes that Charlie is getting worse and Charlie admits that he can't return to their Earth until his mission is completed. However, he believes that Olivia is starting to recover her memories and knows where the head that they're looking for is located.
Olivia meets with Broyles, who warns that the targeted cryogenic companies aren't releasing their confidential client lists so they don't know what head the shapeshifters are looking for. The alteration device they recovered from the shapeshifter that attacked Olivia was broken and Massive Dynamic hasn't been able to figure out how it works. Olivia suggests that Peter look at it, as he has enough engineering knowledge to fake it and get into MIT. Broyles agrees and warns that the shapeshifters may be coming after Olivia. He offers her a bodyguard but Olivia refuses, insisting that if the shapeshifters wanted her dead, she'd be dead.
Walter has the shapeshifter's corpse taken back to the Harvard lab and performs an autopsy. He determines that it's a merge of biological and mechanical material. As he analyzes the shapeshifter's blood, he discovers something startling and tells tell Astrid to call Olivia to check in with him. Meanwhile, Peter analyzes the second shapeshifting device and discovers that it is still streaming data, and contains massive amounts of information. He and Olivia return to the lab and Walter updates them on what he's analyzed the shapeshifter's blood and determined that it doesn't match that of the corpse they recovered from Olivia's attacker. The nurse who died was only a nurse, and the shapeshifter who killed her escaped.
Olivia calls the Charlie shapeshifter with the information. He says he'll get back to her but he has an errand to take care of. He then buys all of the mercury thermometers from a drugstore and drinks the mercury from them, stabilizing his body.
Olivia goes to New York to see Nina at Massive Dynamic. She starts to remember more moments of her encounter with William Bell as she walks through the corridors. She turns the second shapeshifter device over to Nina and asks her to see if she can decipher the data. Nina turns it over to one of her scientists, Brandon, while noting that her research team has concluded that the shapeshifter who attacked Olivia needs his now-broken device to transform, so that shapeshfiter is trapped in his current form. Brandon says that he can decipher the data stream in three hours ands sets up a live data field to Olivia's computer and cell phone.
Peter and Walter go to see Rebecca, the young girl that Walter and William experimented on to give her clairaudience. She invites them in and embraces Walter, glad to see him. She explains that she had the ability to perceive shapeshifters, and thanks Walter for the gift he gave her, but admits that her abilities have faded over the years. Walter suggests that they recreate the experiment to let her regain her abilities and help them find the shapeshifters.
Walter and Peter hook Rebecca up at the lob and prepare to inject her with the drugs. Meanwhile, Olivia asks Astrid to break into Massive Dynamic's FTP site to access the information. As Astrid taps into the information to make sure that they're seeing the accurate data, Walter accelerates the transformation processes in Rebecca. She looks at Peter and comments that she saw him as a baby. As she starts to hallucinate, Peter rings a bell to trigger the sensory rush and Olivia, hearing the noise, collapses to the floor. Walter warns that she's being overwhelmed by the onrush of memories.
William Bell greets Olivia as she arrives in his office in the parallel Earth. He apologies for the crudity of his efforts to transition her over and offers her tea. Olivia suddenly jumps several minutes into the futures and William explains that she's out of sync with the new reality. He notes that she's special and most individuals transitioning over are ripped apart. As time keeps jumping forward erratically, William breathes from a respiration device and wonders how much Walter remembers of their time together. Olivia says that she's learned of the experiments Walter and William performed on her. William apologizes and Olivia informs him that most of the ones he experimented on are in serious mental and physical condition.
As time keep slipping, William explains that he learned that a war was coming and that he needed to create a guardian to prevent people from transitioning between the two realities. He can no longer return to his own reality, and there are only a relatively few people who can transition over. However, the people in the alternate Earth have created specialized hybrid shapeshifters, a "First Wave," who can transition over without harm. Olivia notes that William's company, Massive Dynamic, have been involve din many of the experiments and suspects that William himself set off the inter-dimensional war. When she asks for the truth, William says that it will come out eventually and she doesn't have to trust or even like him to defend their Earth. He offers his unique perspective from having dwelled in both worlds, and asks her to accept him as an ally.
Next, William talks of one final war that will destroy their Earth. The First Wave is looking for a particularly individual who can stabilize the gateway between worlds. Olivia, the strongest of the children they experimented on, is the one who must find the individual before the hybrids find him. William draws a symbol that can be found on the individual and tells Olivia to show it to Nina. He realizes that they're out of time and rings a bell, then recites a Greek phrase that he tells Olivia to tell to Peter when she returns. William warns that Olivia will need Peter's help for what is to come. As he prepares to send her back, he warns that it will be painful because momentum can only be deferred, not negated. Olivia is returned back to her Earth, smashing through the windshield of her car...
Olivia recovers consciousness and tells Walter and Peter that she needs to talk to Nina. She calls Nina at Massive Dynamic and tells her that she has a message from William Bell. Meanwhile, Walter releases Rebecca once the experiment has run its course and tells Peter he wants to take her back himself. As they go, Rebecca stares oddly at Peter and says he has a glow, but then says it must be her imagination.
Astrid is the only one in the lab when the Charlie shapeshifter returns to ask where Olivia is. She tells him that Olivia is going to Massive Dynamic. He notices the FTP download that Astrid is monitoring from Massive Dynamic and realizes what it signifies.
At Massive Dynamic, Olivia shows Nina the symbol but the CEO doesn't recognize it. When Olivia talks about the "last great storm," Nina remembers that William used to speak of the concept. Using two snow globes, she demonstrates William's theory that if the doorway was opened, one Earth would be entirely destroyed in a massive energy storm. Olivia has another memory flash of William writing down the name of Laston-Hennings Cyrogenics. The Charlie shapeshifter calls and sends her a text message warning that Nina is the shapeshifter and that Olivia has to get out of there now. Olivia hastily makes her excuses and leaves, as Nina tells her that Massive Dynamic will lend its complete resources to finding the one who can open the gateway.
Outside, the Charlie shapeshifter meets Olivia as she comes out. He tells her that he has the building surrounded and they'll move in as soon as Olivia is clear. As they move away from Massive Dynamic, Olivia tells him that she knows where the head is. However, she checks her phone as the data feed finishes and gets a picture of Charlie. The hybrid realizes that she knows and drags her into an alleyway. He attacks her and then calls the hijacker to tell him where the head is. Olivia tries to fight back but is easily overpowered until a pedestrian sees them. The shapeshifter shoots him before he can sound the alarm, but Olivia has enough time to grab her gun and shoot the Charlie shapeshifter repeatedly until he dies.
Walter drops Rebecca off at her home. She invites him in but he's clearly reluctant to be near her. She kisses him and thanks him for making her special. Walter tells her that she was always special and leaves to catch the bus.
Broyles tells a grieving Olivia that it isn't her fault that her partner is dead or that the hybrids learned the location of the head. He warns her that the hybrids managed to get to Laston-Hennings and steal the head before the FBI could get there. The cryogenic capsules are gone.
In a secret facility, the hijacker hybrid attaches the stolen head to a body. Head and body rejoin themselves and the leader opens his eyes. Share this article with your friends