When Will Freeman sets off with his twelve-year-old son on a cross-country motorcycle adventure, he thought he knew exactly where the road would take them: California. At least, that was the destination he had planned.

But then they stop in Denver for a night and wind up seeing "The Horse Whisperer" at the movie theater. Unexpectedly, Freeman and his son both feel drawn to ride north instead of west.

Their road, they will soon learn, leads to Wyoming. It is there that they encounter Great Thunder, a Native American shaman. He was expecting their arrival.

Over the next several...