Hiding out from a world overrun by the living dead, fifteen-year-old Samantha (Sam) Grace has grown up on an isolated mesa-top farm. Adding to her difficult life, she now must care for her gravely ill mother as well as her younger brothers and sister. To get medicines to save her mother's life, Sam rides to nearby Las Vegas, a city teeming with zombies, where she happens upon a small group of survivors including Brandon, a young man only a few years older than her. At first, appearing both hapless and helpless, this man's honest and endearing personality grows on Sam. With Brandon's help, Sam tries to leave to return to her family, but the survivor's leader, Priestly, a harsh and conniving man, captures and imprisons them both. Sam ultimately escapes and rides to Brandon's rescue, saving him from Priestly and his men. Amidst an advancing horde of the dead, Sam and Brandon are separated, leaving her hurt and on foot. With the dead closing in, Brandon suddenly appears and saves her from certain death. Together, Sam, Brandon, accompanied by his younger sister, Ally, leave Las Vegas and return to the farm, bringing with them the medicines that save Sam's mother's life. Through her adventure, Sam learns that some people are worthy of trust while others, like Brandon, are deserving of love.