Early in Mystic River, police detective Kevin Bacon pauses while working on a traffic incident on a Boston bridge, and takes a moment to look across the way to his childhood neighborhood. The look on his face–a blend of pity, affection, nostalgia, and fear–foreshadows the feel, if not the action, of what's to come. Now gentrifying at a pace that alarms its working-class residents, the little stretch of riverfront property Bacon used to call home was once a place where law and order often fought to a draw, and where he and another friend watched two men posing as police officers harangue a third friend into leaving with them in the back of their car. Afterwards, the kidnapped boy (played as an adult by Tim Robbins) carved out the semblance of a normal life by tamping down the hurt. His friends continued in the direction they were heading anyway, Bacon siding with the law and Sean Penn siding against it, at least for a while. Each, in his way, remained haunted by the afternoon. Director Clint Eastwood's film adapts a Dennis Lehane novel, keeping its careful attention to how place, family, and local customs shape personalities–and how an instant can change all that. Another unspeakable incident, the brutal killing of Penn's 19-year-old daughter, reunites the childhood friends as men. Heading the investigation, Bacon discovers that a number of locals have no alibi for the night of the crime, but none more suspiciously than Robbins, whose natural meekness starts to look a lot like guilt. In outline, Mystic River is little more than a standard police procedural, but Eastwood and screenwriter Brian Helgeland follow Lehane's lead, letting the action play out at a pace which reveals the murder as a community tragedy which crashes the past against the present. The actors match the gravity of their surroundings, Robbins balancing barely concealed anger with unconcealed pain, Penn beautifully capturing a man who's fought his way into goodness, and Bacon finally finding a role that makes the most of his gift for understatement. It works so well as a showcase for their performances (and those of supporting players Marcia Gay Harden, Laura Linney, Laurence Fishburne, and relative newcomer Tom Guiry), and as a study of their aluminum-sided world, that the inevitable revelations of the mystery plot almost sidetrack a film that's more about fragile lives than clues and plot twists. Eastwood knows this, however, and in his best film since Unforgiven, he ultimately lets observations on character, community, and the tidal patterns of tragedy shoulder a burden an ordinary murder mystery never could.