The Night Medicine — Jody A. Kessler

In 2012, Blackfoot tribal member, Dean Wolfsblood, is the reluctant guardian of a centuries old medicine pipe that makes time travel possible. When Dean's former Marine buddy, Badger Lowell, bribes him to take the arduous trip into the past, the last thing either of them expects during the “Night Medicine” ceremony is for an intruding grizzly bear to chase Kai, a beautiful and complicated Cree woman, into the past with them.
Upon arrival in 1868, the three unlikely companions discover deceit, murder, buffalo hunters, and a kidnapping waiting for them as they travel across mountains and plains to the gold mining town of Helena, Montana. As hidden motivations are exposed, secrets are revealed, and all well-meaning plans for their journey are cast away into the winds of time. Can they survive history and each other long enough to make it back, or will the past change their futures forever?