Claire, back home in California, begins attending college, but is having difficulty adjusting when a mysterious death of a student during the orientation puts her back in the spotlight. In Japan, Hiro and Ando continue their quest to help people with abilities and go so much as to advertise themselves. Meanwhile, Angela fears Nathan/Syler will discover his true identity. Matt tries to settle down back in Los Angeles and raise his son and not worry about unexpected visitors. Elsewhere, Peter is using his ability for good when a mysterious carnival clan, led by Samuel Sullivan, arrives in town which could spell trouble for him and everyone else.

As Hiro's life continues to hang in the balance, he distracts himself with saving the lives of others. Meanwhile, Angela tries to help the new "Nathan" remember his past, at the risk of his remembering too much. Elsewhere, Tracy is determined to get her old job back, but soon realizes that she needs to make more of an impact.

Samuel prepares for new additions to his family, while Lydia warns him of the consequences. Claire discovers that her roommate Gretchen may have a hidden agenda. Meanwhile, Peter finds an unexpected way to connect with Emma, who would prefer to stay distant. Elsewhere, a different side of Sylar emerges as he desperately tries to remember the person he used to be.

Under Samuel's guidance, Sylar starts on a path to rediscover his true identity. Hiro helps Emma accept and understand the great possibilities that go along with having an ability. Meanwhile, Peter enlists HRG to help him find a healer who can save Hiro's life.

H.R.G. hosts a non-traditional Thanksgiving dinner by inviting Claire over at his apartment for dinner. But the dinner becomes more awkward and uncomfortable when Noah invites his former co-worker Lauren, while Noah's ex-wife, Sandra, also shows up with her newest beau, a younger man named Doug Douglas, whom like her also has a small dog fetish. Claire is also conflicted about where she wants to be, in which Noah invites over Gretchen to try to lift up her spirits. Meanwhile, the Petrelli family gets a surprise guest at their table when Sylar shows up having reclaimed Nathan's body and holds both Peter and Angela at his mercy. Elsewhere, Samuel continues to hold Hiro hostage as part of some grand master plan, as Lydia goes to Hiro in search of the truth about Samuel.

Claire attends Nathan's funeral while Peter struggles with his grief in his own way by wanting to seek revenge. Meanwhile, Noah and Lauren interrogate a captured Edgar for information to where to find Samuel's carnival. Elsewhere, Sylar returns to Samuel's carnival where he and Lydia try to find a way to emotionally get inside the killer's head to make him see what is troubling him.

H.R.G. enacts his plan to take down the Carnival with the help of Lauren and Suresh. Sylar visits Matt looking to understand his desire to make a human connection, but Matt has a plan of his own. Meanwhile, Peter warns Emma of Samuel's intentions after his grim vision of the future.

Samuel's ultimate plan spells disaster for thousands.