In the late '70s the mob may have been enjoying a kind of renaissance on the screen thanks to The Godfather, but on the streets it was a different story. Internecine warfare and intensified federal investigations had shattered its hegemony. Among the more spectacular of the latter was that of Joseph Pistone, an undercover FBI agent who infiltrated the highest levels of the New York City mafia in the guise of a diamond fence named Donnie Brasco and over several years collected reams of incriminating evidence.

Played by Johnny Depp, who demonstrates once again that he is the most underrated if not the best of today's young actors, Pistone/Brasco is shadowy, slippery, resourceful, and tormented, a classic figure of modern anomie. His bonds are all based on mutually contradictory identities, and his loyalties are all at odds. In a day's work he'll make contact with lower-level mafia hitman Lefty (Al Pacino), consolidating ties with him by beating the crap out of someone who owes the threadbare don $8000. Next he'll covertly meet with his ferretty FBI overseers at a coffeeshop to hand over tapes of conversations. Then, perhaps, he might call his wife, Maggie (Anne Heche, who brings nuance and strength to what could have been a thankless role), from a phone booth -- the single touch of light and color in a greasy Brooklyn night in what looks like a solitary version of Edward Hopper's Nighthawks -- and ask her to put the phone on the pillow so he can hear her breathe.

Of all these attachments, probably the most deeply felt is that with Lefty -- this is, after all, the testosterone-festering gangster genre. Played brilliantly by Pacino, Lefty is a career capo coming to the end of his line who's just beginning to realize that the mob's retirement plan is rather drastic. Brasco represents slick new blood and a future, and Lefty gruffly but touchingly takes him under his wing and teaches him the rules of the underworld -- which range from proper footwear and the right way to carry money (in a roll, which ends up in Lefty's pocket) to the brutal truths of the leadership hierarchy and the lethal implications of the phrase "to be sent for." Alternately brash and submissive, threatening and vulnerable, Pacino conveys with dark pathos and simmering tragedy the brutal recognition of a wasted life.

His life may be wasted, but it's still of use. Meeting with his colleagues, Brasco announces that he's got Lefty, that he's got his hooks in him. Soon it's obvious that exactly the opposite is the case. As Brasco dutifully compiles evidence on Sonny Black (a leonine Michael Madsen), his nemesis Sonny Red (Brian Tarantina), and the hapless Nicky (Bruno Kirby as an unfunny and unmenacing Joe Pesci), he's drawn into Lefty's grief, humanity -- and violence. As he too predictably announces to the estranged Maggie, "I'm not like them. I am them."

Mike Newell of Four Weddings and a Funeral might seem an unlikely choice to direct a grim eulogy to the gangster genre. But he's also the director of the noirish Dance with a Stranger and the bleakly lyrical Into the West, and he brings to Brasco a puckish melancholy, an acrid humor, and a blithe resignation. A master of visual jokes -- note the scenes involving a commandeered Porsche and a bequested lion -- he also paints the dank winter New York landscape in a sooty impasto that seems to harden around its desperate inhabitants.

More ominous, though, is his depiction of Brasco's employees. The feds are a Big Brother presence from the opening credits -- a montage of surveillance photos that sticks a pin through every character. It's to this that Brasco remains loyal: an inhuman bureaucracy that usurps the natural ties of family -- whether mob or biological -- and rewards him in the end by giving him another false identity. As its title suggests, Donnie Brasco is not so much about crime and justice as the truths of human relationships and the falsehood of what society tells us we are.