Titus Welliver and Amy Ryan in "Gone Baby Gone."

Has this been a good month for movies or what? Already playing are Michael Clayton, In the Valley of Elah, The Assassination of Jesse James by the Coward Robert Ford and We Own the Night. Opening this week are Sean Penn’s Into the Wild and Rendition. Even some of the bigger movies that haven’t been very good are at least targeted to adults—Elizabeth: The Golden Age, Jane Austen Book Club, The Kingdom.

Granted, it’s depressing that the films topping the box office are the worst ones around—Why Did I Get Married, The Heartbreak Kid, The Game Plan. But that’s just the nature of the business. I don’t care if there are a bunch of dumb movies out there, so long as there are at least a few moderately intelligent ones to give the rest of us something to spend our entertainment dollars on.

Which brings me to Gone Baby Gone, a terrible title for a surprisingly good movie. Why was I surprised? Because a) the distributor hasn’t been doing much of a job of promoting it, and b) it marks the directorial debut of Ben Affleck, who—let’s admit it—has been on the critical shit list for most of the past decade.

Believe me that I’m not being unkind when I say I hope that Affleck never acts in a film again, not if he can continue doing work this good as a director.

Gone Baby Gone is adapted from the novel of the same name by Dennis Lehane, who also wrote Mystic River, and this is in the same territory, both geographically and morally.

In Boston’s blue-collar neighborhood of Dorchester, where people still die in the same block where they were born, a four-year-old girl is reported missing. When the police are unable to find any leads, the girl’s aunt and uncle contact private investigators Patrick Kenzie (Casey Affleck) and Angie Genarro (Michelle Monaghan) in the hopes that their local connections may shake loose a little information.

A couple with a personal as well as professional relationship, they argue about taking the case. Angie is afraid that the investigation can have no good end, and doesn’t want the job of finding a small, abused corpse. And her fears aren’t eased when they meet the girl’s mother, Helene (Amy Ryan), a bar hag whose major worry seems to be what the media attention will do to her social life and drug supply. (Think Cheers’s Carla Tortelli minus the redeeming qualities.)

We’re talking real Jerry Springer territory here—when some of the characters are shown actually watching Springer on TV, it feels redundant. Affleck shot on location and used as many locals as possible in scenes (he admits to going into bars to shoot and paying the drink tabs of the regulars, which is cheaper than hiring extras.)

For awhile Gone Baby Gone is filled with a tone of righteous indignation, and that’s never a good thing: Always be wary of someone setting you up to feel morally superior to someone else. Still, everything that Patrick and Angie learn about the case leaves them feeling queasy. So do the cops—the detectives (Ed Harris, John Ashton) working the case, and the captain (Morgan Freeman) who instituted a special Crimes Against Children unit after his own daughter was murdered.

What later becomes clear, though, is that their righteousness is the subject of the film. This is Catholic turf, as the iconography in everyone’s houses reminds us, and it has a strict moral climate. When Patrick’s statement that “Murder is a sin” is met with “Depends who you do it to,” his answer is immediate: “That ain’t how it works—it is what it is.”

I’m giving away nothing to say that the case takes some surprising twists and turns. But at the end of that road is an unexpectedly difficult place. Patrick and Angie have to ask themselves which is better: to do the wrong thing for the right reason, or to do the right thing for the wrong reason?

Some of the music in Gone Baby Gone is a bit on the maudlin side. And that’s the only bad thing I have to say about it.