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

When Walter discovers that Peter has traveled to the alternate universe, he and Olivia gather three cortexiphan children with the ability to transition safely between the two Earths.

In a follow up to last season’s “Peter” flashback episode, the all-new “Six Months Later” episode revisits a poignant period of time for both the Bishops and Olivia.

In an effort to find a way home, Peter journeys to the Other Side to confront Walternate. However, his venture proves more dangerous than expected. Meanwhile, Olivia receives a dire premonition from an Observer.

Peter's visit to the other side intensifies as the alternate FRINGE division faces off against a formidable new foe in a harrowing race against time.