The Problem Child — Michael Buckley

For Sabrina and Daphne Grimm, the latest in a long line of fairy-tale detectives, there is one mystery they want to solve more than all the others: Who kidnapped their parents more than a year ago? Sabrina enters the hideout of the Scarlet Hand, the sinister group of Everafters who are keeping her parents prisoner. She has a chance to rescue her mom and dad but is foiled by the most famous fairy-tale character in the world. How can a human child defeat a magic one? With the help of her little sister (who might be tougher than Sabrina realizes) and a long-lost relative, Sabrina finds a powerful weapon for fighting her enemies, and discovers that magic has a high price.