It’s Labor Day weekend in Swains Creek Pines, and the thin mountain air is filled with more than just the smell of pine and woodsmoke. While the community gathers at the Pavilion for the signature Camp Golden Eagle games and the annual plane fly-in at runway UT00, fifteen-year-old Caleb and thirteen-year-old Sadie are tracking a mystery that begins deep beneath the earth.

Something is thrumming in the shadows of the Dixie National Forest. Sadie is convinced it’s the “Heart of the Markagunt,” an ancient volcanic spirit breathing through the hidden lava tubes of the plateau. Caleb is certain there is a logical, scientific explanation involving the region’s famous “underground water piracy”—but even his technical mind is challenged by the strange, flickering lights and “mountain melodies” in the woods.

The mystery takes a dangerous turn when the legendary Golden Eagle trophy and the airstrip’s critical radio headsets vanish just hours before the big event. With “clueless” adults distracted by BBQ scores and the Kane County Sheriff busy patrolling the village, it’s up to the Junior Detectives to find the truth. From the rugged vistas of Harris Rim to the secrets of Everett Hollow, Caleb and Sadie must stop the sabotage before the first Cessnas touch down on the dirt runway.

Can they solve the crime and save the weekend, or are some secrets of the mountain better left as unsolvable charms?