When one of his forgotten abilities suddenly manifests, Peter and Caitlin get thrown into a crisis situation, and learn first-hand just how deadly the mysterious virus striking people with abilities can be. Suresh, Matt, Nathan, Niki and Bob band together to fend off the "nightmare man's" attack. When West drops by the house, Claire attempts to hide family photos that reveal the man who kidnapped him as a child is her father. Meanwhile, in feudal Japan, Hiro and Kensei's legendary journey takes a dramatic, final turn.

Convinced that the Company is close to finding them, H.R.G. prepares the family to run -- but Claire has other ideas. Hiro returns from the past and learns of his father's death. Grief-stricken, he flings himself into past and makes a stunning personal discovery. After a charged first encounter with Elle, Suresh makes a decision that could change lives. Meanwhile, Matt struggles with his expanding mental abilities. Maya and Alejandro's relationship is tested as they travel with Sylar. Peter meets someone who could unlock his past.