Alpha Dog is an urban drama following the self destruction of Johnny Truelove (Emile Hirsch) and his gang of friends. Living the thug wannabe's American dream of money, beautiful girls and partying in Los Angeles' San Gabriel Valley - their existence is a heady blur of partying and looking for the next thrill.
When Jake Mazursky (Ben Foster) fails to scrounge up the deal money he owes Truelove, Johnny and his gang react by kidnapping Jake's little brother Zack.
Frankie (Justin Timberlake) takes a liking to Zack as the 15-year-old boy eagerly adopts their exciting lifestyle. The situation complicates as Johnny's dad (Willis) and the boy's distraught mother (Stone) pressure Johnny to release Zack.
Johnny realizes that the "adopted" member of his gang is still a hostage and cannot be peacefully returned. Anything can happen and over the course of three days under the hot California sun, something does.
As the story continues to twist, will Johnny commit bigger crimes and truly become the thug he has always idolized?