Ethan Hawke wakes up and kisses his wife good morning as she's nursing their baby. It's a scene straight out of Norman Rockwell, but Hawke is no doe-eyed innocent, he's a realist; he knows that today, his first day as a narcotics officer for the LAPD, will expose him to terrible things he's never seen before. What he doesn't know is that his new partner and mentor will be one of those terrible things.
The partner, played with scene-gnashing brilliance by Denzel Washington, is a study in power corrupting absolutely. He not only knows the game, he changes the rules himself as he goes along, and it's clear that by this time he's been drawn so far in he's no longer aware that there ever was an out. He shows Hawke the drug-glutted streets and then shows him how to turn a tidy profit by all this horror, and he is so magnetic and hip-hop cool that Hawke keeps crossing lines he's drawn only moments before.
To think that the world might actually be run Denzel's way is terrifying indeed, and we pin our hopes on Hawke to pull out of his sudden moral swan dive in time to save not only himself but us. This is a great movie: it keeps you guessing while it's playing out, and it keeps you thinking after it's over.