Late one night, a family stops at a gas station as they return from a recital; another man drives his son home from a baseball game. A young boy steps too near the road; a father swerves his SUV to avoid oncoming traffic.

And hits the boy. And keeps going.

Reservation Road
, the new film from Hotel Rwanda director Terry George, doesn't deal in the clashing of mighty armies or the conflict between nations; it looks at a smaller slice of the world. At the same time, the themes here -- guilt, sorrow, anger, forgiveness -- are explored with power and passion thanks to two extraordinary lead performances. Joaquin Phoenix plays Ethan, a college professor dealing with the sudden death of his son and how that's affecting his wife (Jennifer Connelly) and daughter (Ellie Fanning). He can't go on. He has to go on. Mark Ruffalo plays Dwight, a lawyer who's just drifting through his life -- his job, his shabby apartment, the ruins of his marriage -- and trying to be a good dad to his son (Eddie Alderson). When Dwight strikes and kills Ethan's son, he keeps going -- a single moment of weakness that comes to devour him. He didn't do anything deliberately. But that's no excuse. It was an accident. But it killed someone.

Reservation Road runs between two well-explored pieces of cinematic terrain: The heartfelt family tragedy and the more visceral revenge thriller. Ethan's trying to deal with the pain he's feeling; people keep saying things like "Your Josh is an angel now ..." -- as if that were some kind of consolation. Dwight's tormented by what he's done, yet can't bring himself to do what he knows he has to. At the same time, we do get some of the velocity of a thriller: Ethan wants to know why the police can't seem to find the man who killed his son, and wants to take matters into his own hands; Dwight tries to keep his sin hidden, but events -- and his own guilt -- work against him and force him into choices with desperation and fear behind them.

As Ethan, Phoenix is strong enough to be weak -- to let us see his fury and sorrow and self-pity -- and he also gets one truly great scene. (Ethan may teach politics at the local college, but it's fairly clear he's read Hamlet. ...) There are a few showier notes in his performances, but they still have the ring of truth to them. As for Ruffalo, his work is, if anything, even better -- more rich, more real -- as Dwight tries to come to grips with what has to be done, tries to put the rest of his life right in the wake of something that can never be undone. Dwight is less bad than he is weak -- and one of the pleasures of Ruffalo's performance is watching Dwight himself realize that.

George directs with restraint -- there are a few flashy moments, like when we snap into Dwight's point-of-view as a chance encounter sets his world reeling -- but by and large, the movie's a well-shot, finely-crafted framework made to display the performances within. Connelly is, as ever, excellent, and child actors Fanning and Alderson both deliver some great moments -- simple statements, innocent questions -- that have far more effect than you first think. Reservation Road would probably, ironically, fare better at the box office if it weren't as good -- if Dwight was more of a monster, if Ethan's sadness didn't clearly start eating away at his soul. Phoenix and Ruffalo probably signed on to Reservation thinking that parts this good were few and far between; they were right, and watching the two of them at work is the greatest pleasure Reservation Road has to offer.

(Reservation Road opens October 19th.)