Ridley Scott is no Martin Scorsese, a director who can invest a gangster movie with something extra special to mitigate the blood and gore. And Scott is unlikely to make anything like The Godfather, either. But he is still a highly visual filmmaker who can tackle a story "based on truth" with power and skill, especially when he has good actors to help him out.

American Gangster does not have the innate flair of The Departed, but it is also far less melodramatically inclined. And in Denzel Washington and Russell Crowe, it has two stars who never go the rip-roaring, over-the-top way of Jack Nicholson in the Scorsese film.

Washington is Frank Lucas, the strangely attractive heroin smuggler who became a king of the New York drugs trade in the Seventies by flooding the market with a purer and cheaper version of the drug, procured from Bangkok, and often brought over in the coffins of American soldiers killed in Vietnam.

He did this to circumvent the black and Italian mobsters of the day, and was only caught through the efforts of one of the few cops in New York who wasn't on the take.

Lucas - who was given a shorter stint in prison than he really deserved, after he finally gave the persistent Richie Roberts (played here by Crowe) enough information to implicate more than half of the corrupt New York drugs police - was a consultant on the film. Which is perhaps why he appears a man with a snarling devil on one shoulder and a smiling angel on the other.

Lucas the angel dresses smartly in business suits, looks after his old mum (the excellent Ruby Dee), goes regularly to church, marries well (Lymari Nadal, unfortunately a mere cipher of a part) and behaves like the perfect gentleman until you cross him.

The devil calmly throws petrol over and shoots those who betray him and seems oblivious to the harm he creates on drug-infested streets. His philosophy appears to have been that old one: if he hadn't done it, somebody else would have.

He's an intriguing character, quite the opposite of Superfly and co, and Washington recreates him with a quiet charisma that marks him out in a worthy part.

Crowe's Roberts is a much more familiar denizen of gangster movies. He's the dishevelled but straight cop who has a failing marriage because of the long hours, and is better at catching criminals and philandering with air hostesses than looking after himself or his family. It's a capable performance but works out less satisfactorily because we have seen it so often before.

The two come together at the end of a long movie, and the resultant meeting sparks a dramatic fire which is more formidable than anything that has come before. If Stephen Zaillian, Scott's capable writer, had provided a little more meat for his subsidiary characters, the lead-up to this final confrontation might have been more memorable.

As it is, American Gangster falls short of being a classic and could do with at least 15 minutes out of it, ideally in the first half, which takes an eternity to show Lucas's first essays into crime but doesn't add much to his character. The second half of the film, however, gathers point and pace as Roberts begins to catch up with Lucas who, by that time, had refused the warning of his Thai supplier to quit while he was ahead.

Sharp, observant and true to the period, the film-making is, on the whole, less determined to show its virtuosity than in Scott's other work. No one could call him overly flashy this time.

He is aided not just by Washington and Crowe but by some outstanding character actors including Josh Brolin as a corrupt cop, Armand Assante as the veteran Mafioso who can't quite believe a black American can trump his aces, and Cuba Gooding Jr as Lucas's major rival in the heroin trade.