It's often the first few sentences of a novel that define the rest of the story, and in the case of Gone Baby Gone, it's Patrick Kenzie's (Casey Affleck) opening lines that tell you everything you need to know about his character, his mindset and the choices he'll make throughout the film: "It's what you don't choose in life that make you who you are." He goes on to give examples like family, or where you were born, while the camera sweeps across the hardened blue-collar streets of Dorchester, Mass., eventually landing smack in the middle of a community grieving the disappearance of a little girl who was kidnapped from her bed. Those of us on the outside looking in would describe these people as "white trash" -- the kind of folks that made Jerry Springer a household name -- but to Patrick, this is home. These are the people he grew up with, these are the people he'll grow old with, and these are the people he'll go out of his way to protect.

Patrick knows Helene McCready (Amy Ryan) from high school (he was a freshman when she was a slutty senior), and when her daughter Amanda is kidnapped in the middle of the night, Dorchester is thrown into a frenzy: Cops, news reporters, cameras and crowds of people camp outside Helene's small, unkempt apartment complex. Helene isn't some white, middle-class stay-at-home mom, she's a single woman with an abusive boyfriend and a coke habit. The cops, led by police captain Jack Doyle (Morgan Freeman), begin to do what they do best -- but for Helene's sister-in-law (Amy Madigan), that's not enough. And so she, along with her reluctant husband Lionel (Titus Welliver) seek out the services of Patrick Kenzie and Angie Gennaro (Michele Monaghan); two fairly young private investigators who know the neighborhood, know its people and know how to find someone. And while Kenzie and Gennaro are extremely hesitant at first (after all, every cop in the city is looking for that little girl), they eventually decide to take the case. It would wind up being the single best -- and worst -- decision they would ever make.

Based on the novel by Dennis Lehane (Mystic River), Gone Baby Gone is one of five Lehane novels that feature Kenzie and Gennaro as the main characters. Not only are they partners, but they're also lovers, and their on-the-rocks relationship adds another layer to an investigation that eventually heads in several different directions. When we think Kenzie has solved the case, it keeps going ... and going ... until he's put in a position and asked to make a decision that could tear apart his life forever. Aiding the two private eyes in their quest to find Amanda are two high-ranking detectives, Remy Bressant (Ed Harris) and Nick Poole (John Ashton), who look down upon Patrick as if he were a teenager writing an article for his high school newspaper. We get a sense there's corruption somewhere, but who's lying? Is it Helene, who can't seem to spit out the truth unless she can snort it first? Is it Bressant, who's tough, menacing attitude lacks heart and passion? Is it the Captain, who lost his own child years ago to an abduction and subsequently vowed to protect other children at all costs? It takes awhile to come together, but when it finally does we're presented with a heart-pounding conclusion that will draw tears and whispers, and have you talking for days on end.

For his directorial debut, Ben Affleck was wicked smaht. Not only did he fight to shoot in the Boston area (where the novel is set), but he took a real chance in populating the scenes with locals. He gave them speaking lines, he made them characters -- instead of using actors to portray real working-class people, he asked real working-class people to play themselves. Though it could've backfired, it ultimately payed off big time; every name, every face and every location felt natural, as if we were a fly on the wall overlooking this very real situation. But this was nothing new for Affleck (who also co-wrote the script with Aaron Stockard), since a lot of the same "let's stay local" techniques were utilized in his 1997 film Good Will Hunting. A lot of the dialogue will sound familiar, to a point where you might say to yourself, "So Casey's character from Hunting grew up, and now he's a private detective?" But Affleck chose to stay within his comfort zone (it's worked before), and since the novel is very much about a guy's hometown defining who he is as a man, it's fitting that Affleck would stay close to home for his debut behind the camera.

And the film looks great, thanks in part to cinematographer John Toll (Braveheart), who brings a little bit of beauty to a town filled with dirt, steel and sleaze. The performances are all fairly spot-on; by placing Casey Affleck in the lead role, he's able to work off the Boston locals quite well -- after all, it wasn't long ago that he was a local himself. While you'd expect the film to belong to Freeman and Harris, it's really Amy Ryan who steals the show. I don't know how she prepared, but the woman slipped into the role of Helene McCready -- with her tough street-smart ways and disregard for anything even remotely clean, stable or classy -- as if she had been injected with a double dose of "poor white trash juice" prior to filming. The only sour spot in this otherwise superb cast is Monaghan. It's hard to blame the actress since her character felt underdeveloped and "in the way" most of the time, sort of like they needed a female to be the voice of reason, but then didn't know what else to do with her after that. Perhaps she's more well-defined in the books, but here she's just awkward. And Monaghan adds little energy to the role; coasting through scenes more as an observer, like us, than a crucial part of the equation. But that shouldn't stop you see from seeing Gone Baby Gone. It doesn't appear to have enough juice to land a best picture Oscar nod, but it definitely has enough taste to linger in your mouth, heart and mind for a long time to come.