After a fight at school leaves Marcus facing suspension, Marcus's mother takes him and his younger brother, who has Down syndrome, to Puerto Rico to visit relatives they do not remember or have never met, and while there Marcus starts searching for his father, who left their family ten years ago and is somewhere on the island.

Season Two contains worlds (and alternative worlds) of excitement complete with shape-shifters, cryonic heads, belly-dwelling beasts, and people who turn to ashes before our eyes. But the overarching narrative takes three clandestine FBI agents, Olivia Dunham, Peter Bishop, and Walter Bishop, through a mind-bending investigation of a parallel reality that threatens to destroy ours.

The Fringe team escapes from the parallel universe, except for Olivia, trapped in the other world and replaced in ours by her double, who turns Peter and Olivia's tentative relationship into a love affair.

Who are you? After sacrificing himself to save both worlds, Peter mysteriously returns to ours. But he has been forgotten, by Olivia, by Walter, by everyone. It's as if he never existed. At the same time, shapeshifters controlled by an unknown master begin an onslaught of destruction, and now the two former enemy universes must cooperate to defy a common foe. Fringe's thrilling 22-episode fourth season continues the inspired series' synthesis of astounding...