Three days after a magnitude 6.8 earthquake, the 2,400 residents of Barrow Creek—a played-out silver town in the Nevada high desert—think the worst is behind them. The roads are cracked, the power keeps failing, and help hasn't come. Then people start to vanish.

The quake didn't just split the asphalt. It fractured a basalt cap that had sealed a forgotten karst pocket beneath the town since before human memory. What climbs out of the deep hasn't seen daylight in millennia. It hunts at night. And it doesn't kill what it catches—it carries them down, still breathing, into the dark.

Katie Delgado, the geologist they silenced when she flagged the illegal drilling, is the first to understand what's loose. No one believes her. Sheriff Wyatt Kane has to hold a town that's emptying house by house. A teenage girl barricaded with her little brother learns that the floor itself is no longer safe. And an old miner holds the only map of the tunnels where it lairs—if they dare go down to where it lives.

To survive, they'll have to stop running. And climb, straight at it, into the heart of the fault.

A subterranean siege where the ground gives way and the night eats its own.