In the 1870s, the bonds of friendship between a Lakota warrior, Shadow Hawk, and a US cavalry officer, Joshua Tremaine Mackenzie, were tested as the Great Sioux War intervened. When Hawk's only son is born, he names him Tremaine "Running Deer" to honor his longtime friend. Throughout the conflict, Hawk's belief fades that one climactic battle over the US Army will return the Lakota to its former greatness. He fears for Tremaine's future life on a reservation. Fate plays a deadly hand when Shadow Hawk is mortally wounded in battle. Having lost Tremaine's mother earlier, his worse fears may be realized. In a final act, he makes Mackenzie promise to raise Tremaine in the "white man's world."

"Tremaine" is the story of a Lakota warrior who stands in two worlds, maintaining his connection to his heritage while following the white man's ways. Tremaine's journey takes him from a boy to a man as an expert tracker and guide, a respected Deputy Marshal in the Oklahoma Territory, and a volunteer cavalryman with Theodore Roosevelt's First (Volunteer) US Cavalry Regiment (the Rough Riders) and the charge up San Juan Hill. His association with men like Roosevelt, Leonard Wood, and John "Blackjack" Pershing set a future path at the turn of the Twentieth Century.

Throughout his story, Tremaine must negotiate the highs and lows of being an Indian among the whites. It is a compelling story of clashing cultures and an overwhelming determination to succeed.