They Rise...Out of the flooded streets of Houston, they emerge from plague-ridden waters. Dead. Rotting. Hungry. And as human survivors scramble to their rooftops for safety, the zombie hordes circle like sharks. The ultimate killing machines. They Feed...Houston is quarantined to halt the spread of the zombie plague. Anyone trying to escape is shot on sight - living and dead. Emergency Ops sergeant Eleanor Norton has her work cut out for her.