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 farts
Also 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?