After burying her father in the forest, twelve-year-old Sena realizes she's left alone, perhaps alone on the planet, after a virus has wiped out everyone. Her father left his daughter seven videotapes with important life advice and explanations about the virus. Her journey will be dangerous, as the virus has affected others more terribly than death, turning them into half-humans. Sena encounters them, fights, and tries to survive. Survivors find her, half-dead. Sena carries the antivirus, but it has a strange side effect: Sena periodically loses her memory. That's what her father's tapes are for. Because of her memory loss, Sena can't tell the survivors who she is and that she contains the antivirus. Therefore, humanity is at risk.
