Living in a tree house with your three best friends after the monster apocalypse hits town is pretty awesome. That's how thirteen-year-old Jack Sullivan feels. But when zombies start mysteriously disappearing, Jack and his friends suspect that an extremely evil force is at work. As they search for the missing undead, the kids also complete a Bestiary (that's a fancy way of saying 'monster notebook'), quest heroically (come on, is there any other way to quest?), go to the mall, encouter all sorts of insane new creatures, and pick up a zombie butler named Alfred while they're at it. Now all they have to do is save the entire world and then they can call it a day.