From America to Japan, ordinary people begin to learn that they have extraordinary abilities. Peter Petrelli hopes to convince his older brother that he can fly; a high school cheerleader is indestructible; and a young Indian scientist goes to America in the hopes of proving his father's radical theory of evolutionary advancement.
An L.A. police officer becomes a murder suspect after he hears a voice that helps him rescue a little girl. Claire attempts to avoid the limelight after heroically saving a man's life, and Peter pushes to learn the truth about he and his brother's powers. Hiro discovers a comic book in New York about himself.
Hiro convinces Ando to go with him to New York to try and save the city, while Matt Parkman must convince a federal investigator that he can read minds. Peter's relationship with Simone takes a new turn, and Niki confronts her mother-in-law after making a discovery about her husband.
Claire seeks revenge on the high school quarterback after learning that he is a serial rapist. Hiro and Ando use his abilities to cheat in Las Vegas, and Peter Petrelli tracks down Dr. Suresh. Niki is forced to become a call girl to pay her debts.
Bearing a message from the future, Peter revisits Isaac to convince him to work together. Meanwhile, Niki learns that her husband has been sighted in the area. Matt uses his mind-reading abilities to try and repair his marriage, and Claire confesses to her father what she has done.
Niki's husband returns home with an agenda, while Hiro and Ando are roped into a dangerous game of high-stakes gambling by the man they cheated. Claire meets her birth parents face-to-face, and Mohinder decides to return home to lay his father to rest.
When D.L. runs off with their son, Niki must rely on "Jessica," her alter ego, if she wants to see him again. Claire pleads with her brother not to reveal her secret when he finds the missing video tape. Matt learns that his wife is keeping a secret from him, and Nathan Petrelli asks his family to help him improve his public image.
Hiro and Ando meet an incredibly bright waitress in a diner, and Hiro makes a dangerous decision to try and save her life. Mr. Bennet seeks Isaac's help in saving his daughter, while Matt hopes to help the F.B.I.'s radioactive prisoner. Back home in India, Mohinder mourns his father -- but strange dreams prompt him to press on in his father's research.
Nathan finds the painting that Peter is searching for, sending him to Claire's high school homecoming game in the hopes of saving her from the murderous Sylar. Mohinder makes another life-changing discovery, and Ando waits patiently for Hiro to return from what was supposed to be a quick trip to the past.
Six months into the past Hiro tries to save Charlie's life, and Niki debates letting her father back into her life. Chandra Suresh seeks those who may be evolutionarily advanced, and meets an ambitious young watchmaker. The Petrelli family is put at risk when Nathan is offered the chance to prosecute Linderman.
Matt and Audrey investigate a murder at Claire's high school, leading them to Claire and to Peter Petrelli -- who is now a murder suspect. Niki comes face-to-face her with alter ego when Jessica tries to kill D.L., and Hiro and Ando meet up with the painter Isaac, and set out for New York.
While Hiro goes in search of his sword from Isaac's painting, Nathan hopes to find a way to save his comatose brother. Niki learns that her decision to turn herself in has dire consequences, and Claire hopes to rekindle her friendship with Zach. Mohinder attempts to share the list obtained from his father with the authorities.
Peter seeks training from the invisible man, Claude, while Hiro and Ando flee from mysterious men seeking to put an end to their mission. Matt faces a review board for his actions, and D.L. struggles with his new parenting responsibilities in Niki's absense. Claire tries to locate her biological parents.
As Peter begins his training to learn how to control his abilities, Claire strikes out on a mission to meet her birth mother. Sylar pays a visit to the Bennet home, looking for Claire. Hiro considers the future of his own mission after his father demands that he return home.
Matt Parkman takes a job as a private bodyguard, and becomes a target of Linderman's hired hitman: Jessica. Ando and Hiro try to help a woman in Vegas, while Claire hopes to meet her biological father. Suresh finds someone on the list who is willing to talk to him -- but Sylar gets to him first.
Matt is recruited by the radioactive Ted Sprague and his new ally, Hana, to get answers to their common questions. Mohinder leads Sylar to his next victim, not knowing who the murderer really is. Claire blames her father when her mother falls ill. Mr. Bennet and the Haitian go after Peter and Claude, while Hiro and Ando wind up in the middle of a shoot-out.
Mr. Bennet's past catches up with him when Matt Parkman and Ted Sprague break into his Texas home and hold the family hostage, demanding answers about what he did to them. But when Matt can't control the radioactive man's fury, he chooses to secretly side with Bennet.
Mohinder reveals that he knows more about Sylar than he is letting on, and makes a breakthrough on "the list." Nathan goes to Vegas to confront Mr. Linderman face to face -- and gets help from an unexpected source. Hiro tries to break into a high-security casino to find his sword, while Claire arrives at her new hiding place.
Nathan must consider Linderman's offer to make him President in the face of his plan to destroy New York City. While Matt Parkman and Mr. Bennett try to escape from the company's holding cells, Peter's showdown with Siler ends badly. Linderman drafts a young hero into his dark plans, and Isaac confronts his own fate head-on.
Having travelled five years into the future, Hiro and Ando encounter Hiro's future self and learn that they failed to stop the bomb in New York. When Hiro is captured by the government, Ando and Hiro's future self hope to convince a disturbed Peter to rejoin their cause to change the past. President Nathan Petrelli takes drastic measures to keep the world safe.
After discovering what he might become, Sylar seeks to reconnect with his roots. Hiro and Ando follow him, faced with the necessity of killing him to save New York. Thompson introduces Mohinder to a young girl who he believes is the only one who can stop Sylar, and D.L. and Jessica get Micah back from Mr. Linderman.
With the explosion imminent, Peter and Ted attempt to flee New York City -- while being pursued by Sylar. Nathan makes his choice about whether or not to go along with Linderman's plan, and Niki and D.L. confront Linderman face-to-face. Hiro receives training from the most unlikely of people.
As doomsday arrives, Peter, Matt, Claire and the others head for their fateful conflict with Sylar at Ground Zero. Bennett and Matt discover that the dangerous tracking system is a young girl, and Niki comes to terms with her dual self to save her family.
