Erin O'Reilly

In the climactic season finale, everyone bands together in an effort to stop Samuel (Robert Knepper) from taking the lives of thousands. Peter (Milo Ventimiglia) joins forces with his most unexpected ally to save Emma (guest star Deanne Bray). Meanwhile, H.R.G.’s (Jack Coleman) life hangs in the balance as he and Claire (Hayden Panettiere) find themselves trapped underground with oxygen quickly running out. Elsewhere, Hiro (Masi Oka) starts to come to grips with the decisions he has made and is called into action to help stop a disaster. Greg Grunberg, Ali Larter, Zachary Quinto and James Kyson Lee also star. David H. Lawrence XVII, Harry Perry, Todd Stashwick also guest star.

H.R.G. (Jack Coleman) enacts his plan to take down the Carnival with the help of Lauren (guest star Elizabeth Rohm) and Suresh (Sendhil Ramamurthy). Sylar (Zachary Quinto) visits Matt (Greg Grunberg) looking to understand his desire to make a human connection, but Matt has a plan of his own. Meanwhile, Peter (Milo Ventimiglia) warns Emma (guest star Deanne Bray) of Samuel’s (Robert Knepper) intentions after his grim vision of the future. Hayden Panettiere and Cristine Rose also star. Madeline Zima, Ray Park, Lisa Lackey, David H. Lawrence XVII, Dawn Olivieri, Harry Perry and Todd Stashwick guest star.

As part of a game show, Ann throws a party for her neighbors and gets her purse stolen.