Twelve-year-old Jessica has always longed for a sibling. When she was three, her parents adopted Malcolm, and they became inseparable. But as they grew older, their bond unraveled with constant fighting. To give them a break, their parents take the family on vacation to Maui, where Jessica discovers a hidden world of magical creatures. She keeps it secret—until Malcolm finds out. Determined to exploit the creatures, he teams up with his uncle, risking both the magical world and Jessica’s life in the process.