Copper-Ridge is dying.

When creatures that hunt by vibration begin emerging from the newly-discovered singing stone vein, Steward Kelda Iron-Thorn faces a crisis she cannot solve alone. The traditional methods her grandmother taught her aren't working. The hold's future hangs by a thread.

She needs help from the one person she swore she'd never ask: her estranged brother, Gunnar Stoneheart, who abandoned their family fifteen years ago for the innovation-hungry Thorn-Hold.

Gunnar arrives with experimental technology that might neutralize the threat—and with Brynja, the partner he chose over his family. But as they investigate the deep tunnels, they discover the creatures are drawn to something ancient and imprisoned beneath the mountain. A consciousness that has been sealed away for five thousand years.

A consciousness that witnessed a terrible truth about dwarven history—a truth the ancestors buried along with the witness.