A teenage girl pronounced brain dead wakes up in the middle of the operation to remove her organs... speaking numbers in Russian. When the Navy confirms that the numbers are nuclear launch codes and a missing officer named Rusk knows them, the search is on for the missing man.

When Peter disappears, Walter seeks solace in marijuana. In that state of mind, he and Astrid babysit Olivia's niece Ella, and Walter tells her a fairy tale of a gentle inventor, a stolen glass heart, a detective looking for true love, and a mysterious group of bald men known as the Watchers.

A Chinese Triad is using illegal aliens to breed parasitic worms that eventually kill their hosts. When a ship runs aground, Fringe Division learns of the operation and tries to locate a second ship before the passengers on it suffer a slow, agonizing death.

A state trooper picks up a runaway boy, but when he undergoes a strange transformation, three murders result. The Fringe team is called in to investigate and discover that a small town harbors a horrible secret.

A man in Seattle goes berserk, attacking his boss and claiming his victim is a demon. After the killer dies of what appears to be exhaustion, the Fringe Division discover it's only the first in a series of killings where the persons initiating the attacks were in a dreaming state while awake

Human beings are reduced to ash statues and Broyles realizes that the same person responsible murdered five other persons four years ago... a case that he never solved.

A Dutch industrial consultant arrives for an appointment and dies in a painful explosion of blood. Olivia and Peter arrive on the scene first and discover that the blood contains a pathogen and everyone in the building may be contaminated. While Walter and Astrid work outside the quarantined building to create a cure, the virus develops unique characteristics that pose a danger to the entire world.

A highway construction worker is the seventh in a series of mysterious disappearances in Lansdale, PA. The team come to investigate and finds traces of a mysterious paralytic. Meanwhile, Walter tries to send frogs to an alternate reality and Olivia realizes her recent trip has altered her in ways she can barely understand.

When all of the groom's relatives asphyxiate at a wedding, the Fringe division investigates and quickly ascertain that a human agency is responsible. Walter realizes that the formula for the toxin was based on research conducted by his father, Robert Bischoff, and that the killer isn't stopping with a single test of his lethal concoction.

The team investigate the case of a man who can project electricity... and is at the center of a series of strange deaths involving electricity.

A healthy woman dies of rapid-onset cancer in a matter of minutes, and the Fringe team is called in to investigate. The killer has connections to Jacksonville... and Olivia is a potential victim. Meanwhile, Olivia tries to come to terms with her knowledge of Peter's origins.

Olivia, Walter and Peter are called in to investigate the death of a car salesman who was found in a pool of "goo," exactly like another man across the country. When Walter discovers that the "goo" is brain matter, the trio tries to figure out how the killer can liquefy human brains. As the deaths pile up, the investigation reveals a common thread linking the victims together in an unthinkable manner. Meanwhile, Olivia is horrified when the case places a loved one in harm's way

When an American officer who served in Iraq blows up in a Philadelphia train station, the Fringe Division investigates and determines that something turned the man into a living bomb. Peter and Olivia travel to Iraq to determine if Peter's contacts can shed some light on the situation.

Olivia, along with Peter and Walter Bishop, investigates the strange death of a woman who had an even stranger child. The woman was pregnant for only hours, yet the baby she birthed was fully developed - and also aged eighty years in the span of a few minutes. Olivia asks Nina Sharp of Massive Dynamic for help.

The team investigates a woman that re-appears after weeks of being missing with a rare disease. She also inexplicably causes pain and death to the people she meets. During the investigation, dangerous level of radiation are detected. Walter obsesses about cotton candy; Peter strikes a deal with Nina Sharp; and a truth about Olivia is discovered.

As animal rights activists ransack a laboratory, they get more than they bargained for when one of the caged "animals" unleashes a ferocious appetite. Leaving grotesquely mutilated dead bodies in its wake, the scientifically engineered beast with the body of a lion, claws of an eagle, fangs of a viper, skin of a rhinoceros and tail of a serpent attacks Charlie. With Charlie’s life on the line, Walter must come face-to-face with both his past and the beast.

Two men kidnap a teenage boy using mind control abilities. The boy's father works for Massive Dynamic but Nina insists that the company hasn't been developing mind control, and has no idea who the two kidnappers are. The truth or falsehood of her statements are soon confirmed when Peter encounters the person responsible for the boy's abduction.

In Noyo County, Washington, Peter stumbles across a grisly murder with ties to Newton and First Wave. He is forced to team up with a suspicious sheriff to get to the heart of the case. Meanwhile, Walter has trouble functioning without Peter, and worries he will be sent back to the mental institute.

When a man mysteriously dies by an invisible force, his body rapidly begins turning ghostly white. The Fringe team learns that this is not an isolated incident, and there’s evidence that links the predator to someone who passed away with an unknown genetic disorder. Meanwhile, Olivia suffers from migraines.

The team investigates a bus full of dead commuters that appear to be fossilized and uncover a man who has visions of pattern-related disturbances before they happen; Dr. Bishop requests a piano in the lab to help him process data.

Two young bullies are found dead and in just a few hours they rot to an advanced state of decomposition. The Fringe team investigates and uncovers an amorphous figure claiming more victims. Walter becomes increasingly distracted with his mental state.

As the rogue Fringe team continues to fight off the oppressive Observers’ invasion, unforeseen events lead them into a forest where they encounter a strange subculture of people devoted to recording human history.

Walter thinks the abduction of a young music prodigy is linked back to his old bunkmate at St. Claire's Hospital. When he kidnaps the child he sees a sequence of flashing lights. Olivia wants Walter to return to the mental institution much to Peter's outcry, but Walter's determination to help ends up having chilling ramifications.

The team is called in to investigate why a man jumps out a window because he thinks he's being attacked by butterflies. Olivia gets some breaks in solving the case from her former partner and that she is so desperate to rid herself of him that she demands to go back into the tank. Meanwhile, some former friends and current foes of Peter find out that he's back in Boston.

The Fringe Division is on the case when severely mutilated bodies drained of spinal cord fluid begin to pile up. After their investigation leads them to a scientist with possible ties to the Z.F.T. bioterrorist cell, they are shocked to discover the identity and motive of the killer. When the kills occur with increasing frequency, Olivia, Peter and Walter go to desperate lengths to stop them.