An unexpected volcanic eruption at Crater Lake, the dramatic death of a wanted international munitions dealer at Volcanoes National Park, and a century old, previously undiscovered murder are all part of Special Agent Michael Walker's deadliest case.

Special Agent Michael Walker is called in to investigate the most significant crimes and situations related to the U.S. National Parks. So he is the first one on site when facial recognition software notes the presence of a wanted international fugitive, an international arms dealer, at Hawaii's Volcanoes National Park. When the arms dealer - and the C4 he's carrying - falls to his death in one of those volcanos, Walker thinks the case is over. He couldn't be more wrong.

From there he is called to investigate a just uncovered century-old murder victim, one who might well be noted naturalist John Muir. And that long-ago murder is somehow linked to the conspiracy behind the arms dealer, a massive, unexpected volcanic eruption at Crater Lake National Park, and a range of volcanic activity at other National Parks. With time quickly running out, Walker has to sort out the unlikely connection between a centuries old murder and the deadly conspiracy that threatens thousands of lives.