The truth was buried. Now it’s calling to be found. After uncovering the Hollow Eye and the secrets hidden beneath, Atlas and his loyal dog Moose, believe their detective skills have it figured out. But when an old house on the edge of town reveals new clues about the vanished inventor Elias Flint, the mystery deepens beyond anything they imagined. Atlas begins to unravel the story of The Guardians of the Gear , a secret group sworn to keep powerful machines buried beneath the earth. What they discover will challenge everything they thought they knew about their town, their families, and the dangers that sleep below.