The darkness felt tangible. Like it was pressing against my blind eyes ... We were going to die here. Slowly, slowly.

Two people struggle on a ledge high above the surge pool at Punakaiki's Pancake Rocks. One falls to their death, beginning a sequence of violence as Department of Conservation ranger Matt Grey announces plans for a commercial tourism venture bitterly opposed by the local community. More people die, and it seems their murders are motivated by something more personal than a threat to the integrity of the national park. But the trail is as cold and twisted as some of the park's most labyrinthine caves. Philippa Barnes is asked to do some unofficial sleuthing, which is not welcomed by the police. She delves into the lives of some strong-willed individuals, many of whom have secrets, uncovering a dark story that resonates with events in her own life. But caught in a desperate struggle deep underground, has she run out of time to stop a determined killer?