Alpha Dog

“Alpha Dog” is in some ways a revelatory film. It was written and directed by Nick Cassavetes, whose previous output (“John Q” and “The Notebook,” particularly) has been proficient but strictly by-the-numbers. Furthermore, it features Justin Timberlake in a leading dramatic role. This thing has “mediocrity” written all over it.

Yet here it is, a gritty urban crime drama involving teenagers, guns, drugs and sex, all sharply acted, well-directed and astutely put together, with Timberlake’s performance as one of its greatest attributes. What happened to Cassavetes and Timberlake to make them go this direction, I don’t know, but I’m glad they did. (All due respect to fans of “The Notebook.”)

The film is a fictionalized account of a true story, set in Claremont, Calif., in 1999. The characters are kids with no ethics, no roots and no direction. To the extent that they have parents, the parents are ineffectual. And so their leader is another kid, a teenage drug lord — he can’t be more than 17 — named Johnny Truelove (Emile Hirsch). Johnny has a “Scarface” poster on his wall, and he emulates that character in his business decisions.

His fellow teens, meanwhile, emulate the gangsters they see in rap videos. They’re abusive, sexist kids who cruise from one drug-fueled party to another, always ready to follow orders from Johnny. One boy (Shawn Hatosy) is cleaning Johnny’s garage just because he was told to.

Meanwhile, we meet Jake Mazursky (Ben Foster), a profoundly unstable meth-head who owes Johnny a chunk of cash that he can’t seem to come up with at the moment. His father (David Thornton) and spiteful stepmother (Sharon Stone) won’t give it to him, and his 15-year-old half-brother Zack (Anton Yelchin) — who looks up to Jake like a demigod — doesn’t have it. This debt infuriates Johnny, and a feud ensues. Unable to find Jake, Johnny’s guys, led by a thug named Frankie (Timberlake), do the next best thing: They snatch young Zack up off the street and more or less hold him prisoner.

It’s an odd sort of kidnapping, though. They have no reason to hurt him, just hang onto him until Jake comes through with the money. Problem is, Jake is MIA, leaving Frankie with this hostage he doesn’t really want. Johnny doesn’t want him either, so Frankie is stuck with him.

Zack, for his part, a naive and inexperienced lad, is having a great time going from party to party, being hit on by girls and offered drinks. He becomes friends with Frankie and with Frankie’s associate Keith (Chris Marquette). Frankie takes care of him, brings him along to his dad’s house in Palm Springs, where there’s a swimming pool and a place to sleep. There’s a certain tenderness in the almost brotherly bond that develops between them. But Zack eventually becomes a liability rather than an asset as the spur-of-the-moment kidnapping drags on for days with no resolution in sight.

Timberlake’s performance as Frankie is a standout, emotionally complex and believably street-tough. Anton Yelchin, who starred in David Duchovny’s little-seen “House of D,” is given plenty to chew on as Zack, too, and his laudable performance suggests he may be one to watch.

It’s good to see two other interesting young actors here, too: Emile Hirsch and Ben Foster as the feuding juvenile delinquents. Hirsch (“The Girl Next Door,” “Lords of Dogtown”), whose baby face suggests vulnerability even when Johnny claims to be capable of handling every situation, is the opposite of Foster (TV’s “Six Feet Under”), who plays Jake as a larger-than-life lunatic. When Jake takes a dump on Johnny’s living room carpet as an act of defiance, I have no problem believing it’s something he would do.

Southern California is depicted not as a glamorous wonderland but as a barren wasteland, a desert of stucco-coated houses and ugly chain-link fences. (That’s more or less accurate, by the way.) Cassavetes shoots most of it with hand-held cameras in a documentary style, even framing the story with realistic-looking interviews with some of the figures (including Bruce Willis as Johnny’s uncooperative father). It’s a nightmare of a place, this SoCal, populated by vulgar kids who have seen plenty of crimes committed in movies but have no idea how to perpetrate one themselves.

To some extent, that may be true of Cassavetes, too. His depiction of all this squalor and depravity is vivid, but it doesn’t offer much insight into WHY the kids do what they do, and he drags the resolution out way too long. Still, the fact that the director of “The Notebook” had something this jarringly stone-faced and unflinching inside of him is intriguing. It’s a solid, tragic film about a group of kids whose fate was sealed long before we ever met them.

B (2 hrs., 2 min.; R, pervasive harsh profanity, some strong sexuality, some nudity, some strong violence.)