They aren't exactly likable characters, the drug dealers and stoners and wannabe gangsters of "Alpha Dog."

They're bored, white kids with too much money and time on their hands and, in their shallow estimation, nothing better to do than sit around getting high, playing video games and emulating the speech and bravado of their favorite rap videos. (Every other word is "chill," "dog" or an F-bomb. Word.)

But they feel real and alive in the hands of writer-director Nick Cassavetes?- who couldn't have gone in a more opposite direction from his 2004 weepy romance "The Notebook"?- and whose story of drugs, kidnapping and murder is inspired by a 1999 Southern California case.

The situations become shrill, overlong and a bit repetitive (how many parties can these people attend over a three-day period?) but they also grow increasingly volatile, which allows for vibrant performances from a hot, young cast that includes Emile Hirsch, Ben Foster, Shawn Hatosy, Amanda Seyfried and Olivia Wilde.

Justin Timberlake is surprisingly good as one of the kidnappers?- you already knew he was charismatic and if you've seen him on "Saturday Night Live," you knew he was exceedingly capable of comedy. But here, all buffed and tatted, he succeeds at digging deep dramatically, as well.

His character, Frankie, shares a tangible, unexpected bond with the doomed 15-year-old victim, Zack (Anton Yelchin), who doesn't think he's a victim and is actually thrilled to be hanging out with the cool kids for once?- which makes his story that much more tragic.

Here's how this whole mess happens, which Cassavetes presents as a docudrama, complete with dates, times and places: Zack's older brother, the jittery speed freak Jake (Foster), owes pot dealer Johnny Truelove (Hirsch) about $1,200. He doesn't have the money and can't get it, even after begging his father and stepmother (David Thornton and Sharon Stone) for it.

This sets off a childish, destructive battle between the hotheaded Jake and Johnny and their trash-talking minions, guys who probably weren't all that bright in the first place and whose judgment is even more distorted since they're perpetually under the influence of something.

(All these people have parents, by the way, but they're either neglectful, ineffectual or both. Or as in the case of Johnny's dad, played by Bruce Willis, they enable their children's delinquent behavior by providing the drugs to sell.)

To get back at Jake for breaking into Johnny's house, Johnny, Frankie and their friends kidnap Zack, whom they happen to see walking angrily down the street after a fight with his parents. The lanky, wholesome boy is happy to go along for the ride as they drag him along to Palm Springs for a weekend of partying. He gets to drink, smoke pot and play video games (once they untie him, of course) and even engage in a swimming pool threesome with two beautiful blondes (Seyfried, the dippy mean girl from "Mean Girls," and Amber Heard).

He thinks he is their "dog," and that these guys are his. He finally feels confident, accepted. In the case of Frankie, that's true. But as the days go by and Johnny and his friends start to realize how much trouble they could be in (life in prison, for example), Zack becomes more than just their little pal?- he becomes a liability, then an unsuspecting target.

Cassavetes has been slowly, steadily ratcheting up the tension to this point, and his climax is startling precisely because it's not overblown. (We're not giving anything away here?- the real-life story of murder suspect Jesse James Hollywood has been in the news as recently as last week.)

"Alpha Dog" calls to mind other tense dramas like "A Simple Plan," movies in which regular people make one bad decision, then another and another, until they're completely in over their heads in trouble and find themselves taking drastic actions they never could have imagined previously. The idea may sound melodramatic but the result has realistic bite.

"Alpha Dog," a Universal Pictures release, is rated R for pervasive drug use and language, strong violence, sexuality and nudity. Running time: 117 minutes. Two and a half stars out of four.