Pipe Bearer, a young holy man of the Elk Dog People, sets out with his wife, Otter Woman, on a vision quest to find the meaning of the sacred coloring on a foal born to his mare. The colt bears markings resembling the headdress of a holy man, the medicine hat.

Traveling in the guise of a trader, he leads Otter through the country of the Cheyenne and Arapaho and into the homelands of the Crow and Blackfeet and the enemies of those tribes, the Sioux. When fire strikes the plains, the young couple are joined in their desperate flight to safety by the Arapaho trader, Lone Walker, and his beautiful and courageous Lakota wife, Plum Blossom. Always seeking clues to the meaning of the medicine hat colt, the four meet and observe the customs of many bands.

Driven by fate and circumstance, Pipe Bearer and Otter must make life-and-death choices to survive their hazardous quest.