Seventeen-year-old Emily wants nothing more than to graduate high school and get away from Josh, the jock who teases her mercilessly. But when a virus sweeps through the town after a routine blood drive, leaving over 95 percent of the inhabitants dead and giving the survivors shapeshifting abilities, Josh is one of the few left behind. No longer a teasing jock, now Josh wants to become her ally instead of her enemy.
She doesn't want to let her feelings for Josh grow, but as he insists on protecting her and staying close to her side, she finds herself less able to resist him. They must make their way out of the town together, getting past the people behind the virus and outsmarting their shapeshifting spies. When the time comes for Emily and Josh to flee the town, will they be able to protect their new love from the scientists who want to keep them in cages?