As Noah's life hangs in the balance, Samuel prepares to kill thousands and Peter and the others must band together to stop him and save Emma.

While Peter tries to save Sylar based on his precognitive vision of Emma, Lauren goes after Samuel.

The new and different Sylar pays Matt a visit, while Peter tries to warn Emma that Samuel isn't what he seems. Meanwhile, Noah begins his plan to infiltrate the carnival and capture Samuel.

Sylar visits Claire, while Hiro's past decisions manifest subconsciously due to his brain tumor. Meanwhile, Samuel tries to impress Vanessa, his long-lost love, but things don't go as planned.

While Hiro and Ando attempt to save Suresh, Bennet tries to expose Samuel's weakness in his attempt to defeat the carnival leader.

Claire joins the carnival but begins to suspect Samuel has a secret agenda. Bennet recruits Matt in his battle against Samuel, while Hiro goes to help a friend.

Claire joins the carnival but begins to suspect Samuel has a secret agenda. Bennet recruits Matt in his battle against Samuel, while Hiro goes to help a friend.

Noah gets some unexpected visitors, while Claire arrives at the carnival as Samuel's plans progress. Elsewhere, Peter confronts Sylar and discovers that extreme measures are necessary to stop him.

As Noah hosts a thanksgiving dinner, an unexpected guest visits the Petrellis. Meanwhile, Lydia tries to discover the truth about one of the carnival's secrets.

As Matt continues his battle to resists Sylar's mental domination, Tracy struggles to control her ability and Samuel learns how to tap into the full power of his.

Claire tries to determine who is responsible for the attacks on Gretchen and Annie. Sylar maintains his control of Matt, and Peter uses his newly gained ability to help Emma.

A trip into the past may give Hiro another chance to save the love of his life.

A trip into the past may give Hiro another chance to save the love of his life.

Sylar continues to torment Matt. HRG and Tracy help a young boy who is has suffered many hardships in his life. Claire and Gretchen have a problem with their new sorority sisters hazing them.

Sylar starts to find his true identity. Peter and HRG go on a quest to find someone that can save Hiro.

Lydia cautions Samuel against bringing in new members to their clan. Peter tries to connect with Emma, who wants nothing to do with him, and Sylar struggles to find the person he once was.

Hiro's health continues to deteriorate. Angela takes a gamble by helping the new Nathan regain his memory. Tracy tries to make an impact in her bid to get her job back.

Peter must face the consequences of his actions and also meets a new female hero. Claire deals with others knowing about her abiliy. Samuel fights to find his brother Joseph's memories. When Sylar returns, Matt must struggle with his own inner demons.

As Noah's life hangs in the balance, Samuel prepares to kill thousands and Peter and the others must band together to stop him and save Emma.

Our heroes are trying to find ways to cope with recent events. Some (Claire, Matt) trying to find normality and others (Hiro, Ando, Peter) trying to use their abilities to do good. Angela worries about Sylar, and a new threat arrives in the form of a mysterious carnival.