"Princess Puff wants Robert the Troll's bustling smoothie shop closed. But why? The three glittery gumshoes equipped with brains, sass, and brawn--Trixie, Glinda, and Rue--are on the case. While investigating Puff, the sparkly trio find an even stranger string of clues that lead to none other than Malum, the mysterious unicorn. Malum is suspiciously inventing a new gadget in his stable and keeping it a big secret...and the Sparkle Dragons are determined to unveil just what he's hiding"--Provided by publisher.