Frustrated that their "revolution" never materialized, a cadre of geriatric radicals hatches a plot to blow up hydropower dams in the Pacific Northwest and replicate the great ice-age floods that carved the Columbia River Gorge. They get support through an unexpected alliance with old-line communists, the new incarnation of Russia's KGB, the government of Iran, and a would-be terrorist in Key West who has possession of a cold war era hydrogen bomb. Undetected by Homeland Security, the plot is uncovered by "Swede" Larsson, Town Marshall in Riggins, Idaho (population 406), while investigating the seemingly accidental drowning of a young man in the Salmon River. As the scope of the conspiracy becomes apparent, Swede is joined by his river guide friend Cassidy Pierce and former Vietnam combat pilot Terry Caldwell in a desperate race to prevent a cataclysmic flood.