Sam and Arty are looking forward to summer vacation so much that they barely notice when their bumbling science teacher causes an explosion of purple goo that drenches their classmate, Simon. They're sure Simon will be fine--he looks a little gray, but things like this happen all the time in the town of Sitting Duck.
But Simon is not fine--and totally loses his head when he becomes a zombie! Soon the town is crawling with rabid zombies looking for braaaaaains! The adults are busy panicking and screaming, so it's up to Sam (the leader) Arty (the brains), and their friend Emmie (the rebel) to take charge. If they can't find a cure, it will be a disaster!