A waterborne disease has sprung up in every corner of the globe, decimating the human race. Seventeen-year-old Eli McShane and his friends flee the chaos and violence in Phoenix and journey north toward the rumored location of a safe water source. They add several to their number, including a mysterious girl named Hannah, who, unknown to Eli, is being hunted by a dangerous man. Desperation brings out the worst in many of the travelers, infecting even those closest to Eli. When division comes, will he be able to hold his group together or will each fall victim to their own thirst for survival?