Finn Wheeler, a journalist from New France, Quebec, is assigned to cover the US presidential bid of Senator Joseph Anderton, a charismatic Black politician. Motivated by the discovery of a family heirloom, he decides to combine the assignment with an investigation into the origins of the celebrated rock buffalo monument in North Dakota.

Driving across the United States, he witnesses America in a state of near anarchy as public anger over racial injustice explodes. Once in North Dakota, he falls in love with Evie, a young Mandan woman, and becomes obsessed with 'unriddling' the enigmatic stone buffalo.

Shortly after winning the Republican presidential nomination, Anderton is assassinated, and a deeply-fractured United States totters on the brink of civil war. A shocked Finn reports on the crisis while at the same time struggling to come to terms with his startling discoveries about his ancesteral legacy.