On a warm September evening, college professor Ethan Learner (Joaquin Phoenix), his wife Grace (Jennifer Connelly), and their daughter Emma (Elle Fanning) are attending a recital. Their 10-year-old son Josh (Sean Curley) 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 (Mark Ruffalo) and his 11-year-old son Lucas (Eddie Alderson) 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 (Mira Sorvino), 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.