Scorsese, coming off of Gangs of New York and The Aviator, had hit rock bottom. Perhaps that sounds a bit too dramatic, but Scorsese, once the most influential director of his generation, has spent the last 10 years groveling for Oscars. The movies made money, snagged statues (but never the big ones) and left audiences cold. Gangs was a beautiful disaster, like a box of fireworks set ablaze indoors. For once, instead of trendsetting, Scorsese and longtime editor Thelma Schoonmaker looked like old fogies, panting to keep up where Tarantino, Paul Thomas Anderson and the director's other imitators had outstripped them. The Aviator was hardly better, an expensive, expansive bore — the wrong half of the Howard Hughes story told with lethal self-importance.

DiCaprio, along for both pictures, had struggled valiantly to outgrow his pretty-boy Titanic persona, but the effort backfired. Like watching a teenager trying too hard to fill out his daddy's clothes, he merely reminded us of his limits. As androgynous (if not borderline-effeminate) as a Bratz boy-doll, DiCaprio seemed doomed to fall back on a career of willowy peach-fuzz parts.

Damon, whose post-Good Will Hunting parts have revealed him as a more serious actor than his fellow Oscar winner Ben Affleck, undersold his abilities by taking on the one-dimensional role of Jason Bourne (as smart as the Paul Greengrass-directed sequel was, being stuck playing the amnesiac gave Damon nowhere to go). Meanwhile, the less said about that unpleasant Ocean's 12 debacle (or The Brothers Grimm, for that matter), the better.

Nicholson we love, but all that mugging had gotten to be too much. People still give me dirty looks for defending As Good As It Gets, in which the actor played an idiosyncratic riff on his own persona. It didn't help that follow-ups Something's Gotta Give and Anger Management reinforce the complaint that Nicholson can't turn off the Nicholson long enough to create an original character. The man was becoming a parody of himself.

Put these four together and the whole thing sounds risky. Hollywood has had limited success with Hong Kong remakes, and trusting these guys to do right by something as intricate as Infernal Affairs would be a high-wire act to be sure.

Enter the wildcard: William Monahan, a screenwriter whose debut credit, Kingdom of Heaven, had left him with something of a black eye in Hollywood — unless you had the good fortune of seeing the Ridley Scott cut of Monahan's script. Then you understood the scope of his potential. The man is talented, capable of delivering a crowd-pleaser with intellect beneath the hood.

The uncompromised Heaven addresses 800 years of religious conflict in just under 200 minutes, but Monahan never beats you over the head with it. The Departed works the same way. It's easy to be distracted by the dialogue, the same way Deadwood twists every line to find its most exquisite expression. Or to be swept up in the labyrinthine plot, with layer upon layer orchestrated to recreate the original's intrigue. But it's the subtext that makes The Departed such a rich moviegoing experience — when it comes to what makes these characters tick, the underlying psychology runs as deep as you care to chase it.

"When I was your age, they would say, you become cops or criminals," growls Nicholson, playing Boston crimelord Frank Costello, at the movie's outset. "When you're facing a loaded gun, what's the difference?" Costello might not realize it, but that decision makes all the difference in the world, argues The Departed.

Clean-cut Colin Sullivan (Damon) infiltrates the Massachusetts state police but reports to Costello, enjoying the respectability of honest work while reaping the rewards of his criminal roots. He's cavalier about his cover, renting an apartment well beyond his pay grade and dating the hottest woman from the department, a police shrink named Madolyn (Vera Farmiga).

Meanwhile, hoodwise Billy Costigan (DiCaprio) wants to correct his family's criminal past, enlisting on the right side of the law, only to be reassigned as a mole within Costello's operation. The costs are high as he is thrust back into the crooked life he was so determined to escape, where every day unfolds in constant fear of detection.

A setup like this lends itself to showy confrontations, and the most attention-grabbing scenes feature both characters defying their superiors to see through their double identities: Colin ingratiates himself to Special Investigations captain Ellerby (Alec Baldwin), Billy gets his bandaged wrist re-broken by a suspicious Costello. Scorsese could master these macho encounters in his sleep, but it is the more subtle scenes with Madolyn that reveal just how much both men have given up to role-play their dangerous alter egos: in mandatory therapy sessions, Billy can finally be himself around her, whereas, dating the attractive therapist, Colin can never let her see his true identity.

Such coincidences may seem too convenient (that this shared love interest is all that separates the two men), but they're well within the rules of such a high-concept genre picture. Those who nitpick plausibility may find other flaws amidst the plotting, although if John Woo could get away with having face-swapped rivals shooting one another through a two-way mirror in Face/Off, then none of Scorsese's stylistic touches should phase you (one recurring motif, an homage to Howard Hawks' Scarface, uses not-quite-subliminal Xes to warn the audience when someone's days are numbered).

Scorsese has clearly relaxed. There's an effortlessness about The Departed that's been missing since GoodFellas. Instead of pandering to deliver the kind of movie he thinks people want to see, he's determined to make the most of the material. Where Gangs of New York and The Aviator felt forced, this is what comes naturally to Scorsese. The Departed plays to his strengths, namely the brutal contradiction between the characters' greedy thirst for retribution and their distinctly Catholic guilt (which traces all the way back to Who's That Knocking at My Door?), but also his ability to motivate the most dedicated possible performances from his cast.

Of course, this is precisely the type of movie actors love to sink their teeth into. They get to become characters who are themselves acting at every moment. As con artists tasked with selling the lie of their assumed identities, DiCaprio and Damon get to play all the levels. DiCaprio gets the more conspicuous part, and for the first time since What's Eating Gilbert Grape, I think it would be fair to associate the "O word" with his performance (it's also the first time DiCaprio has convincingly inhabited both the body and spirit of a full-grown man). But it would be wrong to overlook Damon, who hasn't really had the chance to explore his sinister side since School Ties.

Both actors convey the ever-present risks that accompany their dangerous charade. They're playing a grown-ups' game, passing as confident enough among their peers, while allowing us to see the frightened kids staring out from behind his macho façade (Scorsese casts a dead ringer as a young Matt Damon, while even this newly mature Leo reveals terrified glimpses of the insecure youngster underneath). Meanwhile, sterling performances by the entire supporting cast reiterate their challenge to assimilate with the adults around them: Martin Sheen as the paternal detective who sends Costigan into the snake pit, Mark Wahlberg as the abrasive investigator whose protective tactics provide the only buffer between the two men, Alec Baldwin as the weathered officer who trusts his instincts to a fault.

And let's not forget Nicholson, who plays the part as only Nicholson possibly could. That's a good thing and a bad thing, as the actor brings all his eccentricities to bear while chewing the scenery. And yet, would Costello be any less flamboyant — from his leopard-print ties to his dildo-wielding antics — in real life? The character has gotten away with it for so long, he thinks he's invincible, which has earned him the right to behave however he damn well pleases. Contrast that with the meticulously guarded behavior required of both Costigan and Sullivan.

The script doesn't exactly draw these nuances out of the actors so much as it allows the actors to reach deep and draw it out of themselves. But even operating from such a strong foundation, it's important not to discount Scorsese's hand in shaping the script to yield such a relentlessly engaging picture. As the plot escalates to ever-more-precarious levels of complexity (as when Costigan shadows Sullivan to a meeting with Costello, allowing each of the rivals to spy his adversary without quite making out one another's identities), Scorsese keeps things focused on the characters' moment-to-moment fight for survival. We are never less than fully committed to his game of rat-versus-rat.

That's because Scorsese makes the stakes apparent very early. In a quick cutaway to a Costello-sanctioned execution, we see an unknown couple shot one after the other out by the airport. But the violence is anything but gratuitous (it's a shocking sight, but Scorsese cuts away not a second too late). Instead, it reveals just how much rides on the charade: cross Costello, and it's curtains for sure. Michael Mann tried the same trick in Miami Vice, using a ruthless execution early in the movie to establish the ground rules for the final fire fight.

But Miami Vice unspooled with the predictability of the thousand cop films that had come before, while The Departed keeps us guessing. Fans of the original Infernal Affairs may have some idea of which characters will and won't survive, but it's downright astonishing that the "Hollywood version" would have the nerve to follow through — much less up the ante. And every time something shocking happens, there's tragic poetry in the way it couldn't have played out any differently. As Nicholson prophetically warns early in the film, we're all on our way out. "Act accordingly."

[as featured on Collider.com]