Four zombie, rainbow-barfing unicorns were expelled from Pegasia for attempted unicorn cannibalism, but only three of them landed on the mountain where fifth-grader Xander lives with his aunt--but now the unicorns are determined to find their missing friend, Stalor, and when Xander follows them through the portal he finds himself in Shushyerbum, inhabited by Mears with a taste for human flesh, and he not only needs to rescue his friends, but keep from being eaten himself.