It's Jack's tenth birthday and his day isn't going the way he thought it would: he's sprouted wings and can't get down from the ceiling. What's more, he's just discovered that he's a fairy. A real one. With magical powers.He doesn't even have time to get used to the idea, because the world is in grave peril. Why? Because the unicorns have stopped farting. Fact: rainbows come from unicorn fartsAlso a fact: Without rainbows, human happiness drops to dangerous levels. Can Jack and his best friend Charlie persuade the unicorns to parp again and save the world from sadness?