Called a crank and a pseudoscientist by some and a genius by others, Donnelly broke all the rules. When skeptics said he was too green for politics, he got elected Minnesota's youngest-ever lieutenant governor. When they said a politician who prized his Irish heritage could never ascend to national office in a state dominated by conservative Scandinavians, he proved his critics wrong again.

As Zachary Michael Jack' shows, in the latter half of Donnelly's remarkable life, he generated more fame and infamy than he had as a combative congressman. In an uncanny reversal of the usual midcareer doldrums, Donnelly turned political defeat into an opportunity for personal and professional reinvention, remaking himself as a visionary author and a champion of people-first third-party politics. The man known by enemies and friends alike as the Sage of Nininger pushed through poverty and ignominious defeat to introduce the masses to surprising theories about ancient civilizations, world-ending comets, and cryptograms purported to reveal the true authorship of Shakespeare's plays. At root, The Strange Genius of Ignatius Donnelly reveals the story of a man unafraid to speak truth to power, consequences be damned.