The Best Episodes Written By Josh Singer

Walter explains to Olivia how Peter came from the alternate universe, and how he was willing to risk everything to save his son.

Two teenagers turn up dead and evidence indicates that shapeshifters have borrowed their forms for some special mission. While the Fringe team tries to track them down, Peter grows increasingly suspicious of Walter's secretive behavior.

Lightman and Torres interrogate an imprisoned gang leader who claims to be rehabilitated. If the gang leader is freed, he might help fight inner-city violence or return to his life of crime. Foster and Loker investigate the death of a firefighter who was killed in the line of duty.

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”.

The beginning of the end is triggered when Walternate finds a way to wreak havoc “over here."

Santos is working on campaign strategy, Ellie's getting married, Abbey is welcoming guests, Bartlet's making jokes, China and Kazahkstan are about to go to war, Carol makes an appearance, and Josh may get fired.

When a female soldier charges a commanding officer with sexual assault, Lightman is brought to Fort Meade to find out if there's any truth to the accusation. Meanwhile, the Lightman Group is hired to determine whether the young star of a college basketball team accepted a bribe to play for the university.

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.

The Santos campaign meets up with Rock the Vote and lots of musicians are around for a star-studded episode. Helen gives a lecture to MANA (a National Latina Organization, formerly Mexican American National Association) but her heritage doesn't help her when trying to deliver part of the Santos campaign message. Toby is being pressured by the Attorney General, Blake, to reveal his source and it's affecting his relationship with his kids. He tries a little psychological warfare of his own to get Blake to back down. Toby is also giving Josh campaign advice which includes plans to increase courtship of the Latino vote. Elsewhere on the campaign trail, it's Halloween and Toby's kids and Santos' kids are dressing up for the occasion.

The Fringe Team investigates a group of thieves who can break the laws of gravity. Meanwhile, Walter attempts to delay the damage he's caused to the fabric of the universe.

Jed weighs his options for responding to the bombing as Israeli and Palestinian forces face off against each other; Josh has an interesting reaction when Colin arrives at the hospital to visit Donna; Kate and Leo clash over the advice she's giving Jed; Josh assumes a diplomatic role when the Palestinians approach him to initiate settlement discussions; Toby and Charlie prepare a reluctant Jed for throwing out the first ball at Camden Yards; Donna's life is threatened when she develops a pulmonary embolism; Jed reflects on the days prior to his first inauguration.

Valentine's Day starts badly when the Iranian air force shoots down a British airliner, killing 100 passengers. The U.K. Prime Minister threatens to retaliate by bombing nuclear reactor sites, which could doom future support for political reformers in Iran. But C.J. has made an agreement with Abbey to allow the President to get more rest, and she is reluctant to awaken him at 5 A.M. to deal with the crisis. Meanwhile, Toby and a visiting law professor answer questions from a foreign delegation that is trying to write a new constitution for the former Soviet Republic of Belarus, and harried staffers pass the buck of Leo's traditional meeting with the new Miss World.

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

When the Fringe Team visits Massive Dynamic’s assembly of the doomsday device, Walter becomes greatly concerned for Peter’s well-being, so he turns to Nina for added brain power to understand the relationship between Peter and the superweapon. Meanwhile, the discovery of a dead body triggers an intense investigation.

When Assistant U.S. Attorney Zoe Landau, Lightman's ex-wife and Emily's mother, enlists Lightman to help investigate an arson case in which the only eyewitness is a 5-year-old boy, it quickly becomes clear that she and Lightman still have feelings for each other. Meanwhile, Foster and Torres question a rapper who is suspected of murder.

After a terrorist bombing outside of Washington, DC, FBI Agent Ben Reynolds calls on The Lightman Group to help identify those responsible and prevent more attacks. The case takes a personal turn for one member of the team and begs the question of whether honesty is indeed the best policy. Zoe helps Lightman with the investigation and both are concerned about their daughter's safety.

Benson and Stabler investigate the connection between the New York murder of college counselor Kate Simes and her volunteer work at a refugee center working with soldiers tortured in Iraq.

Hannah's world is turned upside down when her husband goes missing, leaving her and his 16-year-old daughter behind.

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.

Hoynes throws his hat in the presidential ring, and asks Josh to join his campaign; Jed's health begins to deteriorate; Toby and Kate head the protocol negotiations with the Chinese over the arrangements for the upcoming summit, which is jeopardized when Jed mistakenly accepts a Taiwanese flag at the National Prayer Breakfast; Bernard takes his new position as head of the Gifts Unit to heart as he gives Charlie a hard time about retrieving the flag so that it can be returned; Josh has his hands full with a pro-Taiwanese senator holding a hard line on recognizing their independence; Bob Russell crashes an Oval Office photo op with the governor of Pennsylvania, who's also another potential presidential candidate.

Benson and Stabler investigate a tutor after a student is beaten and sexually assaulted, but their investigation soon leads them to another student.