Manchester by the Sea is a deeply moving, occasionally wrenching, and extraordinary film. It’s a unique mixture of realism and formalism, in combinations one doesn’t usually find. It also features some of the best acting of the year, including a performance by Casey Affleck that, if he doesn’t blow it with his behavior, is guaranteed to win him a well-deserved Oscar.

Written and directed by Kenneth Lonergan (who has directed only Margaret, released in 2011, and 2000’s You Can Count on Me), the film takes the struggles of a Boston janitor and turns it into art. The story itself could have been the stuff of melodrama: (spoiler alert) disaffected, hard-drinking janitor loses his brother and “inherits” his teenage nephew, a proposition that neither embraces. Other films may well have worked toward that touching moment when they each accept their circumstances and each other, and the viewer reaches for a Kleenex. This is not that film, and the film doesn’t end up there, or go anywhere near there.

To say much more would ruin the joy of discovery, but Lee Chandler (Affleck) has his own demons and rough past, which comes to us in pieces. He also has an ex-wife, played by Michelle Williams (My Week with Marilyn, Blue Valentine) in another brilliant performance. While the story goes back and forth, and branches out in several different directions, the heart of the story is the relationship between Lee and his nephew, played in a star-making performance by Lucas Hedges (Moonrise Kingdom, The Grand Budapest Hotel).

The script has been receiving deserved acclaim. The structure of the film is anything but straightforward, but is clear and emotionally true. The dialogue, is as the case with Lonergan, is so realistic, so unnervingly natural at times, that it puts the artificiality of others films into strong relief. The conversations, the tensions, the awkwardness of real life is on display throughout the film, in nearly every scene.

Lonergan’s camerawork is mostly direct and honest and unassuming. But his editing rhythms are not. He’ll often bring the viewer into a flashback and then out again before we’re even aware of it. He also holds his beats of his shots a little longer—and some a lot longer—than “normal” films, which has the tendency of drawing us into the physical place of the film or the emotional territory he’s exploring.

Even more daring, and unusual, is his use of music. It’s neither “on the car radio” music or background music, but an addition of music over images. Some of the music is classical, some not, some familiar, some not so much. But it transports these scenes to another dimension, and lifts the film during those scenes. The story of the trials and tribulations of ordinary “folk,” in this case, Boston-area workers who also love the sea, is often handled by filmmakers with a touch of condescension, or at least distance. Lonergan’s use of music raises the challenges and emotions of these “ordinary people” into something elevated and exquisite. It’s something that could be badly and wrongly copied, and let’s hope that others who don’t know what they are doing and how stay away from the idea.

Then there are the performances. For those of us paying attention to him, Casey Affleck was the under-recognized brother of a moderately talented actor who turned into a good director. Casey was nominated for a Best Supporting Actor Oscar for 2007’s, The Assassination of Jesse James by the Coward Robert Ford, a respected work with this respected performance noticed by all 12 people that saw the film. For those who haven’t noticed his work over the years, this is a startling and unexpected performance. For the rest of us, it’s merely stunning and one of the best performances of recent years by anyone. Lee is a broken, deeply conflicted and emotionally bound man nearly destroyed by circumstances that is thrown into a new circumstance that puts social, relational and emotional demands on him that he can barely handle. Watching Affleck navigate these moments—some tender, some awkward, some bursting with anger—is a joy to experience. Rarely has there been a recent performance that is so full of painful internal life and is so masterfully modulated by the actor. Some of the great moments are simply Affleck, standing there silent and withdrawn, emoting as powerfully as those actors that love chewing the furniture. Unless he throws the Oscar away through Russell Crowe-like behavior that likely cost that actor the Oscar for A Beautiful Mind, he is a lock in that category.

Williams has a much smaller role, but has nearly as powerful an effect on the viewer as Affleck. Her scene on the sidewalk with Affleck toward the end of the film is one of the best-acted, most heartbreaking scene of two broken people trying to communicate. It’s a scene full of regret, love, unspeakable pain, and a near-complete inability to connect.

Hedges, as the nephew, is getting a great deal of attention, and his performance has the challenge of holding his own against the powerhouse performance by Affleck. This he manages to do, even if he isn’t quite as excellent as others are declaring, especially in his “losing it” scene, which reaches for the stars and only hits the moon. Still, it’s disturbing on some levels that his characterization of a “normal” teenager rings so true. (It’s been a while since I was raising teenagers, and it’s probably more accurate a portrayal than I’d prefer to be aware of.)

The film’s not perfect, but the imperfections are few. There is a fight scene that seems unmotivated. And then there is, sigh, the religious aspect. There is a scene of some minor but important characters (including a surprise casting choice) who are simply described as “Christian,” in this case, meaning religious, and presented as different from the traditional nominal Catholics that are the main characters. And as so often happens in Hollywood, the “Christian” characters’ faith is worn more on the outside than on the inside. There is also the common mistake of throwing in some aspects of classical Catholicism, traditional Protestantism, and evangelicalism in a strange combination that no one practices, but that it seems to represent modern believing Christians to filmmakers. Between the pictures on the wall, the praying, and the behavior, I wasn’t sure what these folks believed. In a film that is so specific about place, employment, behavior and relationships, it’s a misstep and aberration.

But aside from this common mistake, Manchester by the Sea is a powerful, touching, and occasionally devastating film. It’s easily one of the most original mainstream films this year, and Casey Affleck is, at least for the moment, the best Affleck in film.