From the moment Kenzie, played by Casey Affleck, promises a hard-living skank named Helene McCready that he'll find her missing girl, we know he's going to make good on it or die trying. That's what the heroic shamus does in detective fiction: He honors the code a creed somewhat more refined than the law of the jungle, with a higher return of something like justice. But the great strength of Gone Baby Gone, adapted from the fourth book in crime novelist Dennis Lehane's series, is its ruthless undermining of the juvenile good/bad certainties of that code. In his strikingly downbeat directorial debut, Affleck has created something of a blue-moon rarity: an American movie of genuine moral complexity.
Aided by girlfriend/girl-Friday Angie Gennaro (Michelle Monaghan), Kenzie goes trawling for the little girl through an underworld of roughneck bars and drug hideouts, earning the skeptical regard of a transplanted Cajun cop (Ed Harris, all macho authority) and the wary stink-eye of a police chief (Morgan Freeman) whose interest in the case is as personal as it gets. Scared of sliding down a shit trail with nothing but slime and sorrow at the bottom, Angie fears the worst. Kenzie can't let it go. He's made his promise.
It's not giving away much to say that the central crime peters out halfway through the movie, after a botched ransom effort brings only shame. But Kenzie continues his investigation and uncovers a conspiracy of other would-be saviors doing seriously ugly things for all the right reasons. They have a code, too. In a grimly ironic reversal of the detective's role as restorer of moral order, the harder Kenzie pokes around, the murkier and more damning his choices get even the seemingly obvious one of whether to protect the innocent.
As director, Affleck (who scripted with Aaron Stockard) relishes the close-quarters volatility of Lehane's Balkanized Boston, split along myriad fracture lines of class, loyalty, address and ethnicity. The novelist's specialty is the neighborhood noir, in which the (usually sordid) history of a place shadows his characters like the whip hand of doom. Whatever the movie version of his Mystic River lacked in grimy location detail, it captured the book's claustrophobia, the burden of an inescapable shared past that is the mixed blessing of community.
Gone Baby Gone, by contrast, creates a more turbulent, textured sense of the city as a character. The opening credits' somber street-scene montage less a city symphony than a city threnody situates the film in concrete particulars even before it rolls up outside the girl's home, a Dog Day Afternoon madhouse of gawkers, live-at-five news crews, and neighbors momentarily diverted from their grills.
The setting is more persuasive than the plot, which recalls Chandler's gripe that even good detective fiction falls prey to the same contrivances as bad. It hinges upon improbable slip-ups and a naiveté that's unlikely even for the desperate. Indeed, the movie's most generic scenes are all crime-drama standard-issue, although Affleck does invest a familiar ambush scenario with the nerve-rattling use of limited perspective and convincing confusion.
Where Affleck proves unfailing, though, is in the superbly scaled performances that he elicits from his cast, free of the operatic overplaying that occasionally edged Mystic River's needle into the red. That starts with brother Casey, a major talent coming into his own, whose strangled voice and stifled calm make Kenzie a compellingly fallible guardian angel; it goes double for the brilliant Amy Ryan, who embodies Helene as a heedless, pathetic creature of need. From Amy Madigan's too-brief role as the girl's panicky aunt to Southie rapper Slaine as Kenzie's gun-dealing pal, the finely shaded ensemble work is matched by the plangent aptness of the script, as in the etching of a child's no-frills funeral where the casket "had to be returned by the end of the afternoon."
Typically, we want de-tective fiction to translate aberration into a solvable puzzle. Gone Baby Gone instead saves its bleakest ethical quandary for last. Faced with two wrench- ing choices, Kenzie must weigh his own sense of right against what may be a greater good. Yet either way, justice will be shafted and lives ruined. The backbone of the detective's code the restoration of order has rarely seemed so hollow. The ending resonates cruelly in this time of war, as our national susceptibility to clear-cut good/bad options keeps us from frankly considering (or avoiding) likely choices of bad or worse. But that is the scorched earth the detective walks. "It is not a very fragrant world," Raymond Chandler wrote, "but it is the world you live in."