When the father of eight-year-old Corey Jarakeny purchases a metal detector for his son's birthday, he has no idea that the metal detector has been hidden in the store for over twenty-five years. It is not until six years later that fourteen-year-old Corey and his best friend, Will Joviani, finally realize the metal detector's true powers. When Will takes the metal detector for a test drive in Corey's backyard, the device's nonstop beeping leads him to an enormous tree with an ancient symbol carved into its trunk. Corey and Will become curious after an Internet search leads them to believe the symbol signifies material wealth and begin digging around the tree-eventually unearthing an mysterious underground portal. Accompanied by their siblings, Trevor and Kaylee, they embark on an adventure beneath the earth that becomes more dangerous than they ever imagined. As they uncover a mystery that has lifelong consequences, they meet hybrids who are fixated on protecting their land and do not take kindly to anyone who intrudes on their land. In this charming tale, four friends must determine who to trust as they begin a perilous journey to find their way back home from inside a fascinating hidden world.