Under Samuel’s guidance, Sylar starts on a path to rediscover his true identity. Hiro helps Emma accept and understand the great possibilities that go along with having an ability. Meanwhile, Peter enlists HRG to help him find a healer who can save Hiro’s life.

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. enacts his plan to take down the Carnival with the help of Lauren and Suresh. Sylar visits Matt looking to understand his desire to make a human connection, but Matt has a plan of his own. Meanwhile, Peter warns Emma of Samuel's intentions after his grim vision of the future.

Fueled by his vision of Emma in grave danger, Peter attempts to rescue Sylar from his worst nightmare. At the carnival, Samuel reveals H.R.G.s secret past in order to bring Claire to his side. Meanwhile, Lauren makes a bold move to put a stop to Samuel.

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.