Twenty miners are trapped in the Deep Karst — a legendary mine sealed for thirty years after a collapse killed forty-seven dwarves. The air will last seventy-two hours. Standard rescue will take a week.

Sigrid Stone-Breaker, the youngest master surveyor in Iron-Peak's history, assembles a small team to reach the survivors through unmapped tunnels and ancient ruins that predate the hold by a thousand years. The route is unstable, the geology is wrong, and every mile deeper reveals evidence that the collapse wasn't an accident.

Someone planted resonance charges at structural weak points. Someone wanted this disaster.

As the clock counts down and suspicion fractures the team, Sigrid discovers that the Deep Karst holds a secret worth more than Iron-Peak Hold itself — a secret that killed forty-seven people thirty years ago and has been buried ever since.