A better title for this movie might have been, “Cell Phone Usage Within the Irish Mafia in Boston.”

Martin Scorsese’s latest crime drama boasts a gold-plated cast and a compelling story, but while the legendary director is still a master of endearing viewers to his tragically flawed characters, he lets a plot full of one-way phone calls, text messages and computer searches siphon away much of the tension. This is almost more “Firewall” than “Goodfellas.”

The brilliant premise is based on a hit Hong Kong action film called “Infernal Affairs.” Two young men from Boston’s rough South Side choose careers as Massachusetts State Troopers: Matt Damon is a bright, upstanding kid from a solid working-class family; Leonardo DiCaprio is struggling to make a break from his broken home and shady relatives. The catch is that Damon has been groomed since childhood to be a mole for Irish mob boss Jack Nicholson, and DiCaprio gets recruited to go undercover and infiltrate Nicholson’s operation. One’s a cop who really works for the mob, the other’s a mob thug who’s really a cop. Get it?

Besides their connection to Nicholson, the two share a romantic interest in Vera Farmiga, a state psychiatrist who’s drawn to both men. Aside from providing a handy sounding board when DiCaprio needs to verbalize his inner conflict, her character doesn’t sink roots deep enough to matter when the disparate worlds inevitably clash.

Nicholson is terrifyingly entertaining, as always. Without his undeniable magnetism, viewers would have a much harder time accepting the loyalty, respect and fear that motivates everyone in his surroundings.

The numerous supporting roles, mostly within the police ranks, are filled by household names like Alec Baldwin and Martin Sheen. Mark Wahlberg plays a foul-mouthed sergeant who seems to feel that verbal abuse is the only form of communication.

But it’s Damon, DiCaprio and Nicholson who command the screen. Separately, they’re engaging and interesting; when any two share a scene together, the picture fairly sizzles. (DiCaprio especially comes into his own here as the most watchable of the three.) More often than not, though, they’re spending their time making cryptic phone calls, sending secret messages and trying to cover their technological tracks in the course of maintaining their double identities.

If “The Departed” is intended to depict a real American subculture, then it’s depressing that there still exists such brutality, racism, homophobia and organized crime in a middle-class milieu. Taken as a work of fiction, it’s a fascinating character study that might have been even more gripping set in an area with no cell coverage.

With all the subterfuge and double-crosses in “The Departed,” I was challenged to keep the characters’ motives straight, but many of my fellow audience members were simply bewildered – and often they raised their voices well above the soundtrack to confer with their companions: “Who’s that guy? Why did they shoot him? Oooh, they’re gonna find out he’s the rat.”

Please, people. In some films, audience commentary can be part of the fun, but those are the exceptions, not the rule. It’s rude to talk above a whisper during a movie.