In a world where vampires rule and teenaged humans are quarantined as a food source, there's only one choice - resist or die. But fighting Ticks comes at a terrible cost to twin sisters Mel and Lily and their best friend Carter. With Lily exposed to the Tick virus and lying in a coma, it's up to Mel and Carter to search for the cure - and quickly. For with every passing heartbeat, Mel is becoming more and more purely vampire. Now their only choice is to split up in a race to save Lily - and to save humanity.