After the events of the previous year, the Heroes all set out to start new lives: Claire goes to college, Ando and Hiro start a Hero-for-hire agency, Peter becomes an EMT, and Matt reunites with his wife and child. However in the way of these things stands a mysterious carnival owner who begins a quest of his own, Noah wonders if he's ready to form a new Company for dealing with super powered rogues, the Sylar/Nathan "construct" begins to destabilize, and Tracy is murdering government agents.
Claire and her new friend Gretchen investigate the death of Claire's roommate Annie, while Noah comes to Peter for assistance. Samuel and Edgar recover the compass, Hiro realizes his new destiny, and Matt is tormented with mental images from a dangerous foe.
While Claire deals with the revelation of her secret while settling into college, an injured patient sues Peter. Matt gains a new partner while investigating a major drug case. A reluctant new hero emerges and Samuel goes recruiting while visiting his old family home.
As "Nathan" starts displaying new powers, he has visions of an incident from his past involving a young girl and decides to investigate. Hiro tries to save a co-worker and learns a truth about himself. Tracy tries to regain her old life and job.
Songs: Imogen Heap
-- Bad Body Double, Maria Muldaur -- Midnight at the Oasis
Claire and Gretchen pledge a sorority and Claire discovers her roommate has a hidden agenda. An amnesiac Sylar attempts to regain his past, while Peter meets Emma and discovers the nature of her ability. Meanwhile, Samuel prepares to bring a new family member into the carnival.
Songs: Joel Scarbury (Children's Choir) -- Greatest American Hero (Believe it or Not)
Samuel and the carnival take Sylar in but demand a price for their protection. Peter goes to Noah for help in finding a cure for Hiro's brain tumor, while Hiro attempts to help Emma come to terms with her ability.
Matt goes to extreme lengths to get rid of Sylar's mental influence. Noah and Tracy come to Jeremy's aid when the Cainan police hold the boy for the death of his parents. And Claire and Gretchen go on a sorority scavenger hunt only to discover someone is taking it deadly serious.
Hiro's quest to right his wrongs and failures leads him to what he considers his biggest failure, his effort to save the love of his life, Charlie. Doing so without severely distorting the flow of events, however, is far from easy--and complicated by the manipulations of Samuel, whose own agenda is somewhat darker and more self-serving. Meanwhile, Noah in the past deals with his partner from Primatech and his family issues.
Noah and the Haitian arrive to help Claire deal with the attack on Gretchen at the slaughterhouse. Peter comes to terms with his newest mimicked power while helping Emma make a decision about her life. Sylar takes extreme measures to force Matt to tell him where his body is.
Tracy loses control of her abilities and goes to Noah for help. Samuel tells Hiro what he must do to recover Charlie. Nathan and Peter are sent to a storage locker and learn the secret of Nathan's identity crisis. Matt lies on death's door.
Noah meets an old friend while trying to prepare is first Bennet Thanksgiving as a single man. Angela insists that Peter and Nathan join her for a Thanksgiving meal. Samuel begins the carnival Thanksgiving while Lydia convinces Hiro to help her learn the truth about Joseph's murder.
Noah realizes that Claire has stolen the compass and gone to find the carnival, but must deal with several unexpected visitors. Claire and Gretchen arrive at the carnival and Samuel shows them the sights, while Peter goes after Sylar in an effort to get Nathan back.
Claire learns that the carnival holds several dark secrets, and has a showdown with an old friend. Hiro tries to explain to Ando that he needs help, while Samuel seeks out Emma to recruit someone with the power he needs. And Nathan is finally laid to rest.
Claire and Peter try to deal with their personal issues over the death of Nathan. Meanwhile, Sylar returns to the carnival to seek revenge on Samuel, and Noah captures Edgar and attempts to convince him to help stop Samuel.
Noah recruits Matt in an attempt to find Samuel's one weakness. Ando and Hiro try to rescue Mohinder from the asylum, while Peter discovers Emma's destiny.
Hiro imagines himself on trial for using his powers for personal gain, while Sylar visits Claire and Samuel tries to impress Vanessa.
Noah and Lauren launch an attack on Samuel. Sylar asks Matt for his help, while Peter learns what the future holds for Emma and resolves to save her after acquiring help from an unexpected ally.
Samuel reveals the secrets of Noah's past to his daughter Claire in an effort to turn her against him. Meanwhile, Peter enters Matt's mindscape to rescue Sylar, but both men must face their inner demons.
Claire and Noah are buried deep beneath the earth, and must face the possibility that Noah will die. Peter and Sylar must convince Matt that Sylar's repentance is sincere, while Hiro comes to the end of his hero's journey. And Samuel prepares to bring the carnival to the public eye in the most dramatic way possible.