Becca Lang is an average high school girl who happens to be in love with her best friend Natasha. As Becca struggles with whether to tell Natasha how she feels, the U.S. Is attacked. The weapons used spread a fog which kills most, and leaves infected survivors as zombie-like monsters who crave blood. The attack spreads quickly, threatening the entire country, in a matter of hours. Her father puts Becca in charge of getting her little sister Bridget, Bridget's friends, and Natasha to the safety of her uncle's cabin in the mountains of Colorado.