Not since Spacey, Pacino, Jack Lemmon and Alec Baldwin locked horns in Glengarry Glen Ross (1992) have we seen a cast list quite like The Departed. Martin Scorsese, the master and commander of post-70s cinema, returns to the mean streets he likes best in this terrifically entertaining genre picture.

The starting point here is taken from Hong Kong smash, Infernal Affairs. However, screen writer William Monahan, has written this Boston set crime thriller (without having seen the original) using only the basic story beats of the Chinese film, while creating new characters and a whole new set of riffs for Scorsese to work with. It's worth noting: if you haven't yet seen the original, watching this first will bring its own reward by the time the credits role.

The plot's a doozy. DiCaprio plays Billy Costagan, a promising Massachusetts state policeman, who having some knowledge of the 'wrong side of the tracks', is sent deep under cover to infiltrate the local mob, run by Jack Nicholson's Frank Costello. Meanwhile, wouldn't-you-know-it, Costello has been grooming his own inside man for years: he has Colin Sullivan (Matt Damon), the fast rising, steely lieutenant, working against (but pretending to work for) the very special investigations unit that's aiming to take the mobster down. It is less police against organised crime and more like two Irish American tribes going to war.
As each side gets wind of the treachery, and both double agents get involved with the same attractive police psychologist (impressive newcomer, Vera Farmiga), the tension, humour and plot chicanery pile up.   

The Departed is an ensemble movie with juicy contributions from all over of the shop. On the police side alone, you have the paternal figure of Martin Sheen's Queenan, Leo's undercover handler trying to keep the lower ranked Mark Wahlberg in check. Wahlberg is terrific, spitting out insults and wisecracks like staccato gunfire in his native Boston accent. He sets the tone in his first scene; this is a gangster movie full of hilarious banter. You just know you're in for a treat when Alec Baldwin, even in a small part, is also on top form, reminiscent of his paint-stripper cameo in Glengarry. Indeed, Monahan's dialogue reminds of David Mamet at times: all about the male power plays and excoriating put-downs between liquor and gunshots.

Not forgetting Jack. Nicholson works with Scorsese for the first time here and has the time of his life. Jack's Frank Costello is a rambunctious, viagra driven hoot. It's Al Capone as an Irish American pornographer in a leopard skin dressing gown. This isn't an award seeking performance but it's stupendous fun all the same. Jack gives you a sense of riot; you simply don't know what he is going to do next and no doubt his fellow actors didn't either.

On this, his third film with Scorsese (after Gangs of New York and The Aviator) Leonardo DiCaprio is on solid ground, giving his talent full rein with the maturity he now has. His character compels because he lets you see beneath the tough exterior as the strain of undercover work reveals his vulnerability. He's exceptional at that. Matt Damon is also very good as the whiz-kid traitor who constantly has to hold it together under incredible pressure.

The Departed is violent though less brutal than the likes of Casino or Goodfellas. It shows Scorsese on considerable good form, though it is not a serious film exploring issues and themes � and it is all the better for it. The music, production design and set ups all serve the story well, without attaining the pyrotechnic brilliance of early Scorsese. This is a genre movie par excellence. It's an update of those old fashioned, character driven gangster flicks where you can put reality and conscience on hold while you are caught up in the thrill of the chase. Edward G. Robinson and Humphrey Bogart would have relished this Massachusetts caper. The best male cast of the decade is the best remake since The Thomas Crown Affair and vastly superior entertainment.