When an explosion in the Tui Glen cave traps a group of senior students, Gilbert Hastings' partner Christina and the Department of Conservation guide, Kere Hawker, Gilbert Hastings is asked to discover who set the bomb and why. He searches for another way to get into the cave where his partner is trapped. With no hope of immediate rescue, the people underground must find ways of staying alive. On the surface, Jade's daughter Amber is mistaken for the Minister of Mining's grandaughter, Brenna Peebles, and is held hostage to ensure the coal mine at Moa Creek remains sealed in order to cover up criminal negligence. When the kidnappers discover they have the wrong girl staying alive is a game of cat and mouse for Amber as she escapes and is hunted by people who want to kill her. Nerves begin to fray and one young man becomes violent, threatening to kill the whole party. Gilbert has to rescue Christina and those trapped underground, save Amber before she is killed and find the bomber.