Opal Koboi is back, and the power-crazed pixie wants revenge. Her to-do list:- Frame Holly Short for murder - Start a war between fairies and humans - Kill anyone who's ever annoyed her (yes, this includes Artemis)But knowledge of the fairies has been erased from Artemis's mind, and when you don't believe your arch-enemy exists, it can be quite tricky to defeat them.It's unfortunate that Artemis's only hope is a farting dwarf. Enter Mulch Diggums . . .