This week on Fringe, Agent Farnsworth and Fauxlivia cross to our universe after Farnsworth experiences a personal tragedy, while Olivia and Peter try to solve a series of murders.

Since there is no conflict between the two universes in this week's episode, there are several light-hearted moments between Fauxlivia and Walter, and some touching moments between Farnsworth and Astrid.

Twice the Astrid

After a man is diagnosed with cancer, he is approached by a stranger holding a small device who tells him exactly how the rest of his life and death will occur. When the stranger leaves, the man is dead.

Agent Farsworth crosses over to our universe, but as Colonel Broyles prepares a team to retrieve her, Fauxlivia says she may know where Farnsworth is going and she will bring Farnsworth back herself. Farnsworth shows up at Walter's lab, and when Astrid and Olivia show up, Astrid is surprised. It seems Farnsworth has come to see Astrid, not knowing where else to go after her father's death.

Two Unknowns

Olivia and Peter begin the investigation of the man's death, but are stumped as to what could have killed the man. One of the Observers shows up at the scene, seemingly out of nowhere.

Back at the lab, Walter identifies a combination of compounds that shouldn't exist together and Farnsworth suggests that the only way someone would know to combine the compounds is if someone told them to, indicating the intervention of an unknown party.

After a new victim is killed the same way as the first, Peter takes a DNA sample and believes that the victims are inhaling the poison.

Two Futures

Meanwhile, the killer is working as a TSA agent at the airport, writing down the names of his future victims as they pass through his security check point. Later in a parking garage, while an Observer watches from a distance, the TSA agent tries to kill his next victim, telling him he'll be in a car accident and paralyzed from the waist down until he dies alone.

The victim manages to get away, but is hit by a car and left paralyzed, just as the killer predicted.

Using all the compiled data on the victims, Farnsworth figures out they were all checked through airport security by the same TSA agent. At the airport, Peter and Olivia spot the suspect, but lose him when they can't get through security themselves.

Double Trouble

After running a background check, Peter and Olivia learn that their suspect, Neil, was formerly a professor at MIT. While interviewing a former colleague, they learn that their suspect came back from summer break obsessed with high-level formulas, theorizing that time can become flat so that past, present and future could be seen simultaneously.

After learning that Neil spent the summer at his house on Reiden Lake, where numerous time and universe shift events have happened, Peter begins to suspect this all may have something to do with The Observers.

Neil reveals to his mother that he believes God has given him the ability to see into the future, and when Olivia shows up, he forces her to shoot him. Later, a group of Observers find Neil's device that allowed him to see through time, and upon examination, discover that it belonged to September, the Observer who saved Peter's life at Reiden Lake in 1985.

There seems to be a recurring theme of death in the last few episodes, presumably foreshadowing Olivia's potentially upcoming death. Though the best part of this episode is the interaction between Fauxlivia and Walter, who still feels betrayed by her taking Olivia's place to spy on our universe. Early in the episode, Walter refers to her as a viper and Mata Hari, but later comes to see that there's a bit of good in her. What do you think of the recent interactions between the counterparts from both universes?