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.

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.

Peter faces unexpected consequences for his heroic acts and encounters a reluctant new hero. As Claire continues to adjust to college life, she must figure out how to deal with her ability having been revealed. Meanwhile, Samuel moves heaven and earth to recapture the memories of his late brother Joseph. Elsewhere, Matt struggles with his internal demons as Sylar mysteriously resurfaces.

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.

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.

"Tabula Rasa" is the fifth episode of the fourth season of the NBC science fiction drama series Heroes and sixty-fourth episode overall. The episode aired on October 19, 2009.

"Strange Attractors" is the sixth episode of the fourth season of the NBC science fiction drama series Heroes and sixty-fifth episode overall. The episode aired on October 26, 2009.

When Hiro travels three years into the past, he has a second chance to save Charlie from the hands of Sylar. However, Samuel’s presence serves to complicate Hiro’s mission even further. Elsewhere, H.R.G.’s past with his Primatech partner is revealed.

"Shadowboxing" is the eighth episode of the fourth season of the NBC science fiction drama series Heroes and sixty-seventh episode overall. The episode aired on November 9, 2009.

Samuel learns just how powerful he can become and takes dangerous measures to reach his full potential. Meanwhile, as Tracy begins to lose control of her ability, one of her own comes in harms way. Elsewhere, Sylar continues his battle with Matt.

H.R.G. hosts an untraditional Thanksgiving dinner. Elsewhere, the Petrelli family gets a surprise guest at their table. Meanwhile, Samuel continues to hold Hiro hostage, as Lydia goes in search for the truth.

H.R.G. hosts an untraditional Thanksgiving dinner. Elsewhere, the Petrelli family gets a surprise guest at their table. Meanwhile, Samuel continues to hold Hiro hostage, as Lydia goes in search for the truth.

As Claire becomes immersed into the world of the Carnival, she becomes increasingly suspicious of Samuel's motives. Hiro is on a mission to rescue one of his own, but has difficulty communicating his intentions to Ando.

"Let It Bleed" is the thirteenth episode of the fourth season of the NBC science fiction drama series Heroes, the seventy-second episode overall. It is the second episode in a back-to-back series return after the 2009 holiday hiatus. The episode aired on January 4, 2010.

"Close to You" is the fourteenth episode of the fourth season of the NBC science fiction drama series Heroes, and the seventy-third episode overall. The episode aired on January 11, 2010.

"Pass/Fail" is the fifteenth episode of the fourth season of the NBC science fiction drama series Heroes, and the seventy-fourth episode overall. The episode aired on January 18, 2010.

"The Art of Deception" is the sixteenth episode of the fourth season of the NBC science fiction drama series Heroes, and the seventy-fifth episode overall. The episode aired on January 25, 2010.

"The Wall" is the seventeenth episode of the fourth season of the NBC science fiction drama series Heroes, and the seventy-sixth episode overall. The episode aired on February 1, 2010.

Everyone bands together to try to stop Samuel from taking the lives of thousands. Peter joins forces with his most unexpected ally to save Emma. Meanwhile, H.R.G.'s life hangs in the balance as he and Claire find themselves trapped underground with oxygen quickly running out. Elsewhere, Hiro starts to come to grips with the decisions he has made and is called into action to help stop a disaster.