Yellowstone National Park may seem to be a paradise of vibrant hot springs, gurgling geysers, thundering waterfalls, and amazing wildlife, but park ranger Crystal knows better. The Yellowstone Caldera houses a super volcano: one that could blow anytime. Crystal is convinced that trouble is boiling beneath the gorgeous surface, yet no one believes her. That is, no one believes her until Ethan shows up. The two realize that what has drawn them together is their mutual interest in seismology - and in each other.
Suddenly, tremors begin to occur, and the geysers and springs hint at imminent danger. Despite the tension building throughout the park, Ethan refuses to leave Crystal. But what else will come between them? Who else? Can Crystal prove that Yellowstone is about to erupt? Will anyone be able to escape the disaster?