So perhaps “American Gangster,” Ridley Scott’s much-anticipated mobster epic, doesn’t have a single original idea in its head, with its unshakable shades of “Scarface” and “Serpico” and “Superfly.” But it’s exceptionally crafted and superbly acted, with the on-screen combo of Denzel Washington and Russell Crowe unsurprisingly proving impossible to resist, even though it takes about two hours for their paths to cross.

Washington simply radiates as Frank, returning comfortably to the charismatic bad-guy territory that earned him an Academy Award in “Training Day.” And Crowe, who earlier this year was the one playing the stylish villain you love to root for in the remake of “3:10 to Yuma,” is just as powerful as the bulldog on the right side of the law. (Crowe’s third teaming with Scott, following his Oscar-winning turn in “Gladiator” and the romantic comedy “A Good Year,” further demonstrates the extremes of his versatility.)

After toiling loyally for years as the driver to distinguished gang lord Ellsworth “Bumpy” Johnson, Frank steps in and takes over the neighborhood after the old man’s death.

A North Carolina native, he is nattily attired and exceedingly polite, even as he shoots a rival in the head on the sidewalk in broad daylight, but he’s also given to flashes of rage in the face of impropriety. That personalized sense of right and wrong, coupled with his Southern-boy charm, serve him well as he builds his own unique empire.

Tired of relying on Mafia middle men to help him import the drugs he will eventually sell on the street, he just flies to Thailand and finds a way to bring back the heroin on his own.

He made himself a millionaire through the destruction of his own people, urban blacks, doesn’t seem to faze Frank. He becomes a fixture on the nightlife circuit with his effortless smile.

He buys a mansion for his mother (the formidable Ruby Dee), employs his brothers and marries a former Miss Puerto Rico (the luscious Lymari Nadal). But Scott doesn’t let him off the hook – he’s unflinching in showing us the squalor, the decay, the death that result from Frank’s business acumen.

Reveling in wretched excess is, of course, one of the main points of a film like “American Gangster” – the clothes, the homes, the naked women cutting up mounds of powder surrounded by stacks of cash – but so is the down-and-dirty thrill of the hunt. Scott steadily propels both men’s stories toward one another until the tantalizing moment when they finally meet. Then all falls silent and still. It’s a breathtaking scene but it’s also one of the few you’re likely to remember in a film that can otherwise be so derivative.

“American Gangster,” a Universal Pictures release, is rated R for violence, pervasive drug content and language, nudity and sexuality.

• Christy Lemire-AP