The good news is "The Departed" is Martin Scorsese's best film in years. If we don't count his 2005 video documentary on Bob Dylan, he hasn't made a narrative feature this powerful since "Goodfellas," in 1990. But the first thing to say about "The Departed" is that it's not his own creation: it's a remake of the 2002 Hong Kong film "Infernal Affairs," written and directed by the team of Andrew Lau and Alan Mak, and starring Lau and Tony Leung. "Infernal Affairs" was inventive, exciting, and incredibly tense - the story of how the Hong Kong police put a mole inside the city's big criminal gang, while the gang put a mole inside the police department, and how both sides come to realize what's happened but don't know who it is - though we know, which only adds to the tension.

"The Departed" is set in Boston, where the supposed State Police are on the trail of the crime boss Frank Costello, overplayed to the absolute limit by Jack Nicholson with the same kind of gusto he showed as The Joker in "Batman." Leonardo DeCaprio and Matt Damon are the two moles, with Damon smooth and charming, in an updated version of "The Talented Mr. Ripley," and DiCaprio conflicted, tense and frightened, losing himself in the character and giving the very best performance of his career.

The world of the film is a macho maelstrom of constant challenges, fights, curses and rage that give it a testosterone level far higher than anything we've seen in ages - even more than Scorsese's "Raging Bull." Every scene at police headquarters either begins or ends with a fistfight, it seems; and at least some of the scenes in the gang's world end in death, or at least a crippling. The film uses this mirroring very well, and the cinematography by the great Michael Ballhaus is adept at showing the parallels. Ballhaus, by the way, got his start shooting the films of Rainer Werner Fassbinder in the 1960s and 70s, and has the ability to make even the most confusing scenes come clear and meaningful. And once again he and Scorsese are helped here by the editing of Thelma Schoonmaker, who's been Scorsese's editor for almost his whole career.

The film has a subplot that brings the Matt Damon and DiCaprio characters together, and that is the relationship between Damon and Vera Farmiga, who becomes his girlfriend while she's also the court-ordered psychotherapist for DiCaprio's character. Farmiga, who has cheekbones you could slice a steak with, is also a fine actor here, believably handling a role that goes far beyond the standard 'girlfriend of the lead' part.

There's even more to "The Departed" than that; the screenplay deepens the film's texture by adding other characters who are compelling in their own right. Mark Wahlberg plays a police sergeant who despises the slick Damon; Martin Sheen as his captain and Alec Baldwin as the head of internal investigations are both able to hold their own against the stars.

The film is not perfect; as it passes the two-hour mark it begins to repeat itself, postponing what we already know is going to be a cataclysmic climax, so that when the end does come it is almost too quick for its own good, devolving into a by-the-numbers, bing-bing-bing conclusion. Still, "The Departed" is a marvelous piece of work, fine in its own right and a tribute to the mastery of the Hong Kong original.