Every Halloween, the six Herdman kids steal candy, spray-paint other kids, and take everything that isn't nailed down. And this year promises to be the same, until the Mayor decides to up and cancel Halloween. True, that means there'd be no Herdman trouble to contend with, but that also means no candy, no costumes, and no trick-or-treating! Is it possible that the Herdmans themselves could make what looks like a horrible Halloween into the best one ever?