So, there's this Ben Affleck kid that I think you should all pay a lot more attention to.

No, seriously.

I know it's been out for a while now, but Gone Baby Gone has only received modest attention and that's just not right. It's not some kind of lost masterpiece, but it is very good, and that has a lot to do with the director and co-writer who, after a decade and a half of increasingly pointless acting jobs, has finally found his calling. Affleck is not, right out of the box, a master auteur, but for a debut film it's more than solid, and better still it's the kind of work that suggests that he might become really great once he gets a little more practice.

The easiest comparison in the world is with Clint Eastwood, who was six years older than Affleck is now when he directed Play Misty for Me, and whose Mystic River is at least superficially similar to Gone Baby Gone, although a lot of that is a shared milieu (Boston's working class) and a shared source novelist (Dennis Lehane). I won't call Affleck Eastwood's heir, but they work with a similar less-is-more stylistic palette that privileges the actors and the mise en scène, although Eastwood, especially lately, has a significantly better handle on how to manipulate visuals for narrative and emotional effect. Still, Affleck is backed-up by the damn good and typically underappreciated cinematographer John Toll, whose aesthetic is also best described as "less-is-more," and he keeps things looking interesting and oh so realistic.

The story centers around the disappearance of a four-year-old girl and the subsequent tragedy and bloodshed in the lives of her family members and the cops and private detectives trying to find her, but much like in Mystic River, the point here isn't to bicker and argue over who killed who. Instead we get a snapshot of one man's descent into darkness and misery, aided and abetted by a gallery of figures both sympathetic and roguish. That figure in the center is PI Patrick Kenzie, played by the director's younger brother Casey Affleck, an actor who I'm beginning to think is best described by the phrase "national treasure." First there was his scene-stealing turn in Ocean's Eleven and its sequels; most recently there is his film-defining work in The Assassination of Jesse James by the Coward Robert Ford. His work here doesn't equal his work there, which would be quite the achievement, but it does something just as good: proves that his raspy voice and scrawny frame can appear in nearly every scene of a psychologically-oriented crime procedural and not ever come across as less than compelling and believable. Was he cast for reasons of at least partial nepotism? I am certain. But that doesn't keep him from being more or less perfect for the role anyway. He digs deep into the core of what drives the role - Patrick is a kid from the neighborhood who finds himself turning into an outsider because of his investigations into the neighborhood's underbelly - and makes his own physical limitations, that should almost be a liability, into part of the character.

The cast around Affleck the Younger is almost entirely good, although it's honestly surprising to me that the most obscure performers are also the best. The highlights are Amy Ryan, Amy Madigan and Titus Welliver (yay Deadwood vets!) as the missing girl's family, particularly Ryan who starts out as pure trash before moving into an area of more refined tragic dimensions, all while embodying the Boston lower-class in one of the least-cartoonish depictions of that culture that I've ever seen on film. Michelle Monaghan is a bit less believable, look too much like a movie star as Patrick's lover and colleague Angie, but her character is the primary driving force behind the film's psychological arc, and she carries that off perfectly. Only Ed Harris as an increasingly mysterious cop feels "acted," not least because of his goofy beard; only Morgan Freeman, as the head of the missing children division of the Boston PD, feels lazy, although if you were Morgan Freeman at this point in your career, you'd probably be tempted to coast too.

The specifics of the plot are not something I care to spoil, but the narrative structure is rather interesting, because it turns out to be something rare in American films: a two-act structure. Or rather, it's a structure that I don't think quite has a name, but I tend to think of it as "H"-shaped: an expansive opening act that constricts into a narrow central channel before expanding again into an extended denouement. I'm not being vague on purpose, I promise. Let us say that the plot sidetracks itself a bit more than midway through, and briefly appears that it's going to be something completely different from what it was, and it ends up being yet a third thing. It's a good structure, let's leave it at that.

Presumably, that was already present in the source novel and thus Affleck and co-writer Aaron Stockard (making his own debut) shouldn't be credited with it. But I am perfectly happy to credit them with the detail-obsessed script that takes the instantly-recognisable cadences of lower-class Boston and comes up with perfect naturalistic dialogue, giving characters things to say that most of us have probably never heard but that come across as true to both the people and the setting. It's a significant step up from Affleck's Oscar-winning work on his last co-written screenplay, Good Will Hunting, which has always struck me as a bit too pithy and precious for its own good, and like his restrained direction speaks to a bright future in social realism.

I must confess to being more than a little blindsided by this movie. It is more than competent, it is genuinely moving and emotionally harrowing. It's easy to look at years of tabloid-friendly misadventures and Surviving Christmases and Daredevils and presume that The Ben is a callow hack. But Gone Baby Gone is the work of a smart and humane filmmaker at the start of what I genuinely hope is a long career. God help us.