FBI agent Lincoln Lee insists on helping Olivia investigate a series of killings by a translucent man who left his victims in the same condition. Meanwhile, the two worlds exchange information and Walter is haunted by visions of a mysterious man in his mirrors.
composed by Prokofiev, performed by Ukraine National Symphon -- "Cinderella In The Palace", Bobby Day
-- Rockin' Robin
A serial killer on the Other Side has killed 23 victims and Fauxlivia comes to This Side to ask for the loan of the serial killer's duplicate, a mild-mannered Forensics Psychologist. Meanwhile, Walter deals increasingly vivid hallucinations.
Songs: composed by Berlin Philharmoniker -- "Kyrie from Requiem" composed by Mozart, Mozart -- "Requiem In D Minor"
Songs: Violet Sedan Chair -- Seven Suns (Rising), Up Down Up -- Wild Eyes
The Fringe team investigates a man with a broken neck who was drained of his pigmentation. Meanwhile, Olivia suffers from headaches and Peter begins trying to recreate the Machine.
Violet Sedan Chair. -- Long List Of Lovers, Bryan Ferry
-- Me oh My
Songs: The Airborne Toxic Event -- Changing, Tommy James & The Shondells -- Crystal Blue Persuasion
Peter reaches an uneasy alliance with the Other Side's Fringe Division, and helps them once they capture the mastermind behind the shapeshifters. Meanwhile, the Other Side's Elizabeth Bishop comes to see This Side's Walter Bishop to ask for his help.
The Fringe team discovers a girl who can see the future, and she warns that her vision always come true. Now, Olivia and the others must find the source of her newest vision, which shows a courthouse collapsing and killing hundreds of people.
Songs: Mayer Hawthorne -- The Walk
While the Fringe Division on This Side deals with a murderer who uses a poison that can't possibly exist, Agents Farnsworth and Dunham from the Other Side come to pay the team a visit.
Songs: Little Feat -- Dixie Chicken, Mozart -- Violin Concerto No. 1 in B-Flat Major, K. 207: II
While Olivia deals with the ramifications of the memories of Peter's "Olivia" subsuming her, the Fringe team investigates the deaths of two couples and discovers that a twisted killer is trying to capture love in a bottle.
When a passenger on a Paris-to-New York flight transforms at the NY terminal and kills two TSA agents before dying himself, Peter realizes that the case is the same as one that he dealt with in the original timeline four years earlier. Meanwhile, Olivia is put on leave when Broyles discovers that 40% of her memories as an agent for him are now missing.
Songs: Peter Noone
-- I'm Into Something Good, Dawes -- Time Spent In Los Angeles
Feeling left out on This Side, Lincoln travels to the Other Side to help Fringe Division investigate a vigilante who genetically damages his victims as he kills them.
While dealing with multiple cases of spontaneous combustion, Walter realizes who is responsible for Jones' plan and sets out to get proof. Meanwhile, Jones launches a series of new attacks after the bridge is shut down, in his bid to create a new universe for himself and his superior.
Peter and Olivia attempt to stop William Bell from destroying the world, while Water is forced to watch. However, to save two universes, one of them will have to die.