When you tackle the novels of Dennis Lehane, whether as a reader or a filmmaker, you have to be willing to go into some dark, nasty places. Mystic River was certainly an example, and the new movie of Gone Baby Gone is another.

In fact, the darkness Lehane put on the page is at times too much for Gone director and screenwriter Ben Affleck. As much as he delves into the horrors of child abuse and abduction that Lehane explored, at a couple of crucial points he pulls back, as if to say that there is only so much an audience can bear.

And that's just part of the problem facing Gone Baby Gone. It is quite effective in some respects, including its presentation of a grimy and poor side of the Boston area and its people. But at other points it falters, although one of those missteps can be laid at Lehane's door.

Gone Baby Gone (sometimes written as Gone, Baby, Gone, the way a character uses the phrase in the book) is based on the fourth of Lehane's novels about the private-eye team of Patrick Kenzie (played by Affleck's actor brother Casey) and Angie Gennaro (Michelle Monaghan).

When a little girl disappears, it seems as if every police officer in the region is on the case, as well as the local media. But the girl's aunt (Amy Madigan) is convinced more can be done, and asks Kenzie and Gennaro to help. In an area where people are chronically suspicious of the police, the private detectives' local roots may get them through doors and into conversations unavailable to the law.

Reluctant at first, the detectives agree to help and are soon enough wrapped up in the Please see 'Gone', D5

Continued from Page D1 mess of family, cops (including two tough detectives played by Ed Harris and John Ashton), thugs and some of the worst people you can imagine. The horror they encounter preys on Kenzie and Gennaro, and puts them on a path where morality and the law are in conflict.

Ben Affleck, making his directing debut, has a good feel for locations and, most of the time, for actors. You can tell the latter by the presence of strong players like Ashton, Harris, Madigan, Morgan Freeman (as the leader of the missing-girl investigation) and Amy Ryan (as the missing girl's worthless mother).

Casey Affleck does well as Kenzie, although he seems a bit more boyish than Lehane's creation, who has seen plenty of terrible things by the time he gets to Gone Baby Gone.

But Monaghan's Gennaro is a problem. Some of this comes from how much you know about the books, where Gennaro also has a long and rough history that shapes her decisions in Gone, but which is not as clear in the movie. But some of it also comes from the sketchiness of her character, on the page and in the film, which leaves Monaghan with too many blanks to fill in.

The plot, streamlined a bit from the book, has its twists and turns, some of which you'll figure out easily, others that are not so readily evident. And Affleck plays fair with a key confrontation late in the story, even though it may prove a downer for many in the audience.

The cumulative result is an acceptable but not entirely satisfying movie, an uneven effort but hardly a career-ending one. Affleck shows enough skill as a director to keep at it, and enough promise that he can surpass Gone Baby Gone.