There will be some uneasy thoughts lingering in most viewers’ minds after seeing Clint Eastwood’s “Mystic River.”

This is a piece of filmmaking that seethes an unshakable emotion, an unnerving power that exists well beyond its beginning and end. It’s amazing, probing and also very, very frustrating.

Sean Penn, Tim Robbins and Kevin Bacon star as three childhood friends who share a chilling event that would prove to cloud their entire lives. As adults, they’ve grown apart: Jimmy, played by Penn, runs a convenience store. Dave, played by Robbins, struggles with his past, family and alcoholism. Sean, played by Bacon, is a homicide detective who is married to his job instead of his wife, who has fled town with their daughter.

Jimmy is an ex-convict, working-class father who, after his daughter’s murder, vows vengeance on the man who took her from him. Dave is suspected by both his own wife, played by Marcia Gay Harden, and Sean, who heads the investigation, of killing Jimmy’s daughter.

This film benefits from many things, most noticeably a strong cast.

Sean Penn is miraculous as Jimmy. He’s played characters much like this one, though his performance here is much more dynamic. Not only look, but also listen to this guy when he realizes his daughter is dead. Look at his face when he says he can’t cry for her.

Penn will undoubtedly receive the most praise, but he’s not the only performance worth mentioning. What a role this is for Kevin Bacon, who for years has been comfortable in the role of “the creepy guy.” He plays someone with much more color and vulnerability than he has in the past.

Essentially, he’s playing the role Eastwood would play if he were thirty years younger. Bacon deserves praise for doing what most actors wouldn’t do: He shows real emotion rather than sobbing it all out.

Despite remarkable performances, “Mystic River” is all Eastwood. He again applies the formulas that work for him: A relatively simple story among complex and intelligent characters, mixed with his craftsman-like approach to filmmaking. He always provokes, intending his audience to follow clues and assume for themselves. This is what makes Eastwood’s film so rewarding; he doesn’t spell it out for his audience.

The problem here is that Eastwood directs his film like the surprises are stunning revelations, when in actuality if any viewer has paid attention to the first hour’s obvious allusions, he or she would catch on.

This is where the film’s lethargic time frame grows weary: Characters slowly begin to look less dimensional and take some awkward turns. Like Eastwood’s “Midnight in the Garden of Good and Evil,” the presence of so many characters overwhelm its overall effect, and when one important female character pulls a Lady Macbeth in one of the final scenes, it’s all the more detrimental to the time a viewer has invested.

Instead of being smacked with the emotional tides that have more than waded in, we’re left with a big “Huh? What the hell?” that proves to be a tremendous blow to the influence of the film. It’s a conclusion soaked in miscalculation that quickly evolves into a competition of bitter beer faces.

Yet, “Mystic River” is an undeniably good film. Eastwood hasn’t come close to making a film of this magnitude since his masterpiece, “Unforgiven,” but it’s doubtful he’ll ever outdo that film. This one, however, may over time come close.