Jake Hoyt (ETHAN HAWKE) is a young cop who wants to join the L.A.P.D.'s narcotics team. To do so, he's assigned to a training day where he's to ride with veteran detective Alonzo Harris (DENZEL WASHINGTON) who will see if the rookie has what it takes for the job.
Informing Harris that he'll do whatever he asks of him, Jake expects a routine day of instruction and limited action, and he initially gets just that as they make a drug bust. When Harris makes Jake smoke some of their confiscated evidence, however, he quickly realizes this won't be any regular training.
As the day wears on, Jake meets many of Harris' varied associates, such as old friend, Roger (SCOTT GLENN); disabled drug dealer, Sammy (SNOOP DOGG); and menacing thug Smiley (CLIFF CURTIS). Seeing the veteran interacting with them and living and acting by his own set of rules, the rookie cop must decide if his new partner for the day is just testing him or truly is a renegade detective with his own agenda and plan for dealing out justice.