In the Hong Kong crime picture released here as Infernal Affairs (2002), a gangster grooms a young man to be a mole in the special police unit that is trying to shut down his operations. At the same time, a super-secret undercover cop infiltrates his gang. The suspense lies in whether the dirty cop or the undercover plant will figure out the other's identity first.

It's a heroic romance in which the good cop and bad cop are cracked mirror images of each other, but it's fairly dimensionless as romance — i.e., it is not "about" the moral confusions surrounding undercover work. Though the good guy and the bad guy are each disguised as the other, the values nonetheless remain melodramatically polarized. About all there is to engage you is how it's going to be resolved this time around (only one of the cops remains alive at the end, but their personalities are ironically reintegrated — a "tragic" happy ending). In sum, the concept is nifty and the movie runs a sleek 101 minutes.

Martin Scorsese's The Departed transplants the story to Boston where the police are trying to bring down a mobster named Frank Costello (Jack Nicholson) who has bullied his way to dominance over the working-middle-class Irish neighborhood where he runs a protection racket, a dope ring, a fencing operation, etc. The undercover cop Billy Costigan (Leonardo DiCaprio) and the mole Collie Sullivan (Matt Damon) are also Boston-Irish and Scorsese and screenwriter William Monahan seem to be reaching for an epic vision of Irish-American corruption in the cradle of American liberty.

You catch the sociological sprinklings — a quotation from Joyce (improbably identified by a 12-year-old); Freud's statement that the Irish were impervious to psychoanalysis; the fierce refusal of a bereaved mother to "rat out" her son's killers. But the moviemakers haven't changed the narrative significantly, and the fact that the same story and characters originated in a movie set in Hong Kong should have told them that whatever they were accomplishing by lengthening the movie to 152 minutes they were not by the same process deepening it.

The Departed isn't victim to the self-deception by which Scorsese and screenwriter Wesley Strick spread a little guilt among the "good" characters to make Cape Fear (1991) worthy of their efforts. But it's indifferent enough, a project made with the kind of nondescript moviemaking skill any big-budget generalissimo would be capable of. The Departed is ambitious yet shallow, bloated yet weightless.

Scorsese appears to have believed he could turn a slick gangster picture into an Irish Godfather. I didn't get a feel for the local circumstances that produced Costello and his minions, however. The scene in which Costello recruits the child Collie by buying groceries for his mother is too simplistically illustrative, like the Warner Brothers gangster pictures of the '30s in which the fact that a boy trips a girl on roller-skates for fun is enough to tell us that he'll grow up to be no good. As for Billy's background, we learn it from an abusive grilling by an undercover recruiter (Mark Wahlberg) who is convinced that Billy is too erratic to be a good cop above-ground. This is Wahlberg's best scene, but the exposition about Billy is too clearly announced. Whether showing or telling, the movie is clumsy and obvious. (To do Warners justice, Marked Woman (1937) starring Bette Davis as one of the prostitutes who helps convict the gangster based on Lucky Luciano, has a more nuanced sense of situation than The Departed.)