On a warm September evening, college professor Ethan Learner, his wife Grace, and their daughter Emma are attending a recital. Their 10-year-old son Josh is playing cello -- beautifully, as usual. His younger sister looks up to him, and his parents are proud of their son. On the way home, they all stop at a gas station on Reservation Road. There, in one terrible instant, he is taken from them forever. On a warm September evening, law associate Dwight Arno and his 11-year-old son Lucas are attending a baseball game. Their favorite team, the Red Sox, is playing - and, hopefully, heading for the World Series. Dwight cherishes his time spent with Lucas. Driving his son back to his ex-wife, Lucas' mother Ruth Wheldon, Dwight heads towards his fateful encounter at Reservation Road. The accident happens so fast that Lucas is all but unaware, while Ethan -- the only witness -- is all too aware, as a panicked Dwight speeds away. The police are called, and an investigation begins. Haunted by the tragedy, both fathers react in unexpected ways, as do Grace and Emma. As a reckoning looms, the two fathers are forced to make the hardest choices of their lives.

A story set against the Mountain Meadows Massacre, the film is based upon the tragedy which occurred in Utah in 1857. A group of settlers, traveling on wagons, was murdered by the native Mormons. All together, about 140 souls of men, women and children, were taken. Amidst this, two young lovers-to-be, one a Mormon and the other one of the doomed settlers from Arkansas, develop a relationship in an atmosphere of suspicion and rancor.