Centers on the events leading up to the cataclysmic 1980 eruption of Mount St. Helens in Washington, with the story beginning on the day volcanic activity started on March 20, 1980, and ending on the day of the eruption, May 18, 1980.

The beautiful but unfaithful wife of a successful lawyer meets her untimely end at their anniversary dinner. After a suicide note is found soon after her death, it seems more likely that she was murdered, as all the dinner guests had good reason to want her dead.

War veterans visit a lakeside cabin for a week of shooting, drinking, etc. but find the cabin being looked after by a young caretaker named David. When David's status as a war deserter is revealed, all hell breaks loose.