Hoping to reignite their relationship, college students Emily and Randall arrive at their weekend getaway only to discover a peculiar older couple already staying there. They all agree to share the home but, after an indulgent night of partying, they're awoken to a living nightmare of apocalyptic proportions. A mysterious airborne microbe has infected the water and it's making its way to the house.

A dog is desperate to get a message to his owner in the hospital, but he cannot get inside. He asks a cat to deliver it to the little boy and thus begins a long chain of creatures great and even microscopic trying to get word to the boy. This book even introduces children to the concept of antibodies and microbes.