After a teenage girl is pronounced brain dead, her mother takes her off life support, but when doctors operate quickly to remove her organs, the deceased girl shockingly awakens screaming an alphanumeric code. Equally as perplexing as her resurrection is that she is now somehow able to speak Russian and possesses classified information only a high-ranking soldier would know. While the girl's mind-bending condition intensifies, Walter dusts off some old lab videos and hypothesizes the unthinkable, sending Olivia and Peter to investigate the bewildering case.
Following an unexplained attack involving disfigured humans, the Fringe team visits Edina City, a small town in upstate New York, to uncover leads surrounding the bizarre case. When it's determined that these disfigured people have managed to hide themselves for a while and they'll do just about anything to keep it that way, the investigation takes an unexpected turn.
When a man enters an office in Boston for a meeting, he becomes disoriented and collapses, only to have his veins erupt and spray blood everywhere. Shortly after Olivia and Peter arrive at the scene to investigate the bizarre case, it's discovered that a lethal virus - with deep ties to something very valuable - is spreading, so the CDC moves in to quarantine the building and eradicate the pathogens. Isolated inside with the rest of the exposed office employees, Peter and Olivia face life-threatening circumstances, sending Walter, Broyles and Astrid on a frantic ...
The Fringe team are puzzled when a specific group of guests are targeted at a wedding.As the investigation goes the team is at a loss as to how the toxin was delivered and targeted.As they gather evidence and taken back to the lab, it's discovered that the wedding ceremony was a testing ground for a weaponed science experiment. Adding to the intense lab investigation, Walter uncovers an alarming formula that reveals a link to a branch on the Bishop family tree. With the escalating threat of more deadly attacks and unexpected familial ties to the case, the Fringe team ...
After a violent tremor shakes a Manhattan office building to its core, leaving only one survivor who leads the Fringe Team to believe he is not from this reality. Walter surmises that what shook the building was not geologic, but rather something discovered by him and William Bell many years ago. With another catastrophe imminent, the team races to Jacksonville, the site of Walter and William's experiments, forcing Olivia to face her mysterious past in an effort to save hundreds of people from certain death.
Walter flashes back to 1985 while explaining Peter's otherworldly origins to Olivia. Also, Peter's mother is introduced, and details of the neighboring world reaffirms that there is more than one of everything.
When a perfectly healthy woman is found dead from a disease she never had, the Fringe team investigates the origin of this inexplicably fatal condition before it claims more innocent victims. Meanwhile, Olivia struggles to keep Walter's secret from Peter, and her loyalty to Peter is tested as time goes on.
When passengers aboard a commuter train appear to have died a still death, it seems that a switch was flipped because all cell phones, mp3 players, laptops, batteries and bodies have been drained of power. As the Fringe team assembles at the bizarre crime scene, Peter remains suspicious that something is amiss with Walter, who is struggling to keep the unimaginable a secret. When the investigation leads them to Alistair Peck, a very powerful man who has tremendous energy with severe consequences, an ironic set of circumstances surface
When two teenagers on a date turn up "dead" at an abandoned warehouse with the three puncture wounds to the soft palate - a trademark of the shape-shifters - the Fringe team investigates the evidence as well as the motives of mastermind Newton. Upon discovering a shape-shifting embryo, Walter returns to the lab to conduct further analysis, and Olivia and Peter head to Massive Dynamic for answers. Meanwhile, Peter reveals a family secret to Olivia as Walter struggles to recall what Newton knows about "building a door."
Peter teams up with a local law enforcement official, Sheriff Mathis, on a serial murder investigation with ties to Newton. Meanwhile, Walter copes with the possibility of being sent back to St. Claire's, and someone from the "other side" pays a visit .
After the extraordinary turn of events that shockingly left an imprisoned Olivia "over there," she fights to find her way home. Meanwhile, Peter and Walter try to move on with their lives unknowingly alongside alternate Olivia.
The story alternates to the Fringe Team "over here" where they investigate a mystifying case that people are discovered in a trance-like state that ultimately leads to their death. The unlikely suspect: a mysterious box. As Peter and Walter collaborate to study its properties, alternate Olivia presses on and turns up the heat on an unsuspecting Peter. Meanwhile, key information about the future is revealed when Walter and Nina meet at Massive Dynamic for the emotional reading of the last will and testament of William Bell.
In this case, timing is everything as a series of anomalous events lead the Fringe Division to investigate deadly incidents with unimaginable coincidences. As the freaky crimes continue to occur, the team is in a race against time to protect potential victims. Meanwhile, Secretary Bishop shares his strategic plan with Colonel Broyles as Olivia grapples with a heart-stopping vision.
Newton, concerned about the consequences of a distressing development involving a high-ranking official, is forced to call to action a sleeping shapeshifter. As Walter and the rest of the team gather evidence, they move the investigation to Massive Dynamic, where Olivia goes on high alert and Walter finds himself in a perilous situation.
The alternate universe Fringe Division investigates a shocking breach of security when a twin frees his brother from a quarantined Amber area. As the team sets out to crack this sophisticated case, Walternate experiments over there more with Olivia as she reenters the tank. Meanwhile, visions of Peter continue to haunt Olivia about returning to the "other side."
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.
When a serial kidnapper "over there" strikes again, the emotional and familiar case hits home for Colonel Broyles, sending a determined Olivia to uncover additional details about the abductions. In the meantime, Olivia fights on and reunites with Henry to enlist his services on an intense and covert mission to return home.
When the Fringe Team investigates a case where a victim had his heart extracted, it's just the beginning of a series of mysterious and reanimating events tied together. Meanwhile, Peter comes to terms with the reality of his relationship with Olivia.