In the shadow of the Blackridge Mine, fourteen-year-old Halcyon Flint has always heard the mountain's whispers. But when a dare gone wrong traps her in its collapsing depths, those whispers become screams.

With her flashlight dead, her ankle shattered, and the air running thin, Halcyon's only lifeline is the faint glow of a stranger's journal—one that belonged to her mother, a geologist who died in a cave-in years ago. Except the journal tells a different story. Her mother wasn't killed in Utah. She died here, in Blackridge, chasing the same silver vein that now threatens to bury Halcyon alive.

Above ground, her father, Frank, races against the storm with a rescue team led by hard-edged Captain Catherine Ward. But Frank knows the truth: the mine's instability is his fault. His lies about his wife's death lured Halcyon into the dark, and every drill strike risks burying his daughter deeper.

As the mountain's veins fracture and floodwaters rise, Halcyon uncovers relics of her mother's final hours—and a path to survival etched in courage and betrayal. Below, she battles crumbling stone and suffocating doubt. Above, Catherine and Frank clash over how much to risk for one life.