The Sparkle dragons : one horn to rule them all

Summary/Review: "Help! Sparkle Dragon alert! Princess Puff wants Robert the Troll's bustling smoothie shop closed. But why? The three glittery gumshoes, equipped with brains, sass, and brawnTrixie, Glinda, and Rueare on the case. While investigating Puff, the sparkly trio finds 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. Sparkle, shine, glitter go!"--