Fan-favorite writer and producer Bryan Fuller returned for the second half of Season Three ("Fugitives") and helped to lay much of the groundwork for Season Four before leaving the show for good. The shocking events of last season's finale, which saw the death of Nathan Petrelli whose mind was then placed into the villainous Sylars body by resident telepath Matt Parkman, really shook up the Heroes status quo.

Season Four ("Redemption") picks up six weeks later with all the main characters moving on with their lives: Peter is a Paramedic, Claire is off to college, Nathan is learning more about his "new" abilities, Parkman is tortured by visions of Sylar due to the transfer and Hiro is dying. Things are going to get even crazier when the Carnival, led by the mysterious Samuel (Prison Break's Robert Knepper), rolls into town complete with an all new band of freaks including a tattooed woman, an elderly time traveller and a knife thrower played by Darth Maul himself, Ray Park.

Source: Popular Mechanics