Driven apart by a childhood trauma, three men meet again when Jimmy's daughter is murdered, cop Sean investigates and loner Dave emerges as a likely suspect. Soon an air of vigilantism begins to poison their Boston neighbourhood.
Mystic River's apology for vigilante action is certainly disturbing, as any notion of guilt is quickly washed away in a rather unconvincing coda. But fans of the director will also breathe a sigh of relief that, after the disappointments of Blood Work, Space Cowboys and True Crime, this marks a genuine return to form.
Two things make Eastwood's task easier for him: a superb cast and a cracking source novel. Dennis Lehane's book is one of the very best thrillers of recent years, richer in Boston detail and closer in character study than anything Eastwood manages to bring to the screen.
That said, Brian Helgeland does redeem himself somewhat after his lacklustre adaptation of Michael Connelly's page-turner Blood Work. The screenwriter seems to understand the ageing director's desire to sacrifice plot pacing for loose, character-based meandering, and so places key points of information and discovery at appropriate intervals in order to keep even the most casual viewer hooked from the first frame.
He's faithful enough to Lehane's original material to also ensure that this story of a lingering human evil, capable of destroying lives in both past and present, retains a degree of moral complexity.
Eastwood takes a break from duties in front of the camera, leaving the stage free for Penn, Robbins and Bacon to strut their stuff. Penn delivers another multi-layered performance as a man in whom rage, grief and honour suffer a head-on collision, while Bacon sheds his psycho baggage as a cop caught in a compromising position.
Robbins, with the toughest role, is worst served by Helgeland's script, which cuts much-needed background from the book. We should find more sympathy for his character, as fate snaps its man-trap jaws around him, but even Robbins' best efforts can't quite fill in the gaps. Dave is supposed to be living proof of the way in which child molestation infects the victim and, by degrees, those closest to him; but by reducing his impact and this theme in the movie, a more routine and far less powerful whodunnit structure emerges in its place.
Nevertheless, the combined efforts of all three actors add psychological weight to the revenge-driven murder mystery. Despite secondary status, the women in the cast also strengthen the show, particularly Marcia Gay Harden's heartbreaking turn as a woman caught between love and disgust as she fears her husband's troubled past has mutated him into a killer.
While not quite the equal of the novel, it's more complex, emotionally-charged and better acted than the average Hollywood thriller.