Xander and the rainbow-barfing unicorns

"Xander contracts the mysterious virus of the Rainbow-Barfing Unicorns. The virus gives the unicorns their barfing abilities, but it's draining Xander of any color at all! Xander's fate lies in the hands, er, hooves, of Ronk, the most dimwitted of all unicorns. This is not good. In fact, this is bad-- really, really bad"--Back cover.

"A swarm of insects threatens the Montgomery Orchard and Xander's fruitful summer job. Luckily, the so-called bugs aren't actually bugs. Unluckily, they're unicorn-hating fairies from Pegasia! If Xander and his unicorns can't rid the orchard of these pests, their secret will be blown like a stomach-load of multi-colored chunks"--Back cover.

Xander Stone has been hiding his three friends the Rainbow-Barfing Unicorns in plain sight as part of a magic show, but now a regular unicorn has found her way through a portal; problem is the virus that turned them into zombie-like creatures has apparently given his three friends a craving for unicorn flesh--so when they all use to the portal to return to Pegasia Xander follows to try and restrain his friends (especially Ronk), and solve the mystery of who has been stealing candy from Pegasia.

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.

Everybody thinks that the "ponies" in Xander's magic show are made to look the way they do (like zombie ponies) with tricks and make-up, but the eccentric billionaire Russ DeVon knows what they are (the unicorn part, at least) because when Russ was nine he discovered Pegasia, and was kicked out for trying to steal a baby unicorn--and now he will stop at nothing to get back there.

Just when fifth-grader Xander Stone decides to give up his long search for magical creatures, he encounters three Rainbow-Barfing Unicorns, who were banished from the magical world of Pegasia after an encounter with a mysterious object leaking green gas turned them into smelly, zombie-like, rainbow-upchucking creatures--and Xander will need to keep his wits about him if he is to hide the true nature of his new friends from other humans.