Iconic film-maker Martin Scorsese's latest crime and mafia caper, "The Departed", premiered in New York City Tuesday night (September 26), with the star-studded cast of the film as well as other supportive celebrities crowding the red carpet. The film, a remake of a Hong Kong hit, "Infernal Affairs", brings together a wide array of leading male actors - Jack Nicholson, Matt Damon, Leonardo DiCaprio, Mark Wahlberg, Alec Baldwin and Martin Sheen. Set in Boston, "The Departed" centres on the ongoing battle between the Massachusetts State Police Department and the city's top organized crime syndicate, run by mob don, Frank Costello (Jack Nicholson). Rookie Billy Costigan (DiCaprio) is assigned to infiltrate the mob while Colin Sullivan (Matt Damon), a young police officer, in turn, is working secretly for Costello. Critics have been appreciatively comparing "The Departed", not as much with Scorsese's 2002 crime drama "Gangs of New York", but with some of his earlier, more notable films like the 1973 "Mean Streets." On the red carpet, Scorsese said that he was fine with that comparison, explaining that he has an affliction for exploring the underworld. "I seem to really get involved with, when I read the script, I got involved with the whole idea of this underworld and the idea of trust and betrayal, so I just became obsessed with that, and went with it," said Scorsese. DiCaprio, who has teamed up with Scorcese before, pointed out how this Mafia drama/thriller is different from the film-maker's previous films on similar subjects. "He's traditionally sort of done Italian Americans, either in Vegas, New York, this is sort of the Irish mob underworld, dealing with the police department, corruption, the FBI, information, disinformation, moles. It is a gangster genre film but it's something he's sort of never explored before and I think he was really intrigued and challenged to do something different like that," said DiCaprio. The actor added that it was a different experience for him too because he felt like he was making two different movies at the same time, with Damon's character and his own having their own elaborate story plots. DiCaprio also spoke about his upcoming film, "Blood Diamond", set in 1990's Sierra Leone, reported to depict the uglier side of the diamond trade industry in Africa and already attracting questions over whether this is an indictment of well-known large diamond companies in that region. When asked about "Blood Diamond" and the questions the yet-to-be released film was raising, DiCaprio said he was hoping a lot of people would see the movie for themselves to realize and understand its focus. "This is a depiction of a real time and situations that happened in Africa and no one's denying that and people should just look at it as a way of understanding what sometimes happens when corporations go into less fortunate countries and what happens to the people there and the environment. And I think the movie's going to be a real powerful film, I really do and I think it's going to say a lot about the world we live in," said the star. As for Matt Damon, for his role in "The Departed", the actor actually spent some time with the Massachusetts State Police, even accompanying them to at least one drug bust. Reflecting on his time spent with the Boston cops, Damon said, "That was a real fun part for me to learn, to meet those guys and kind of explore that sub culture and learn about what they do. I had kind of a leg up because I'm from Boston, so I didn't have to do a lot of the requisite kind of research about the city because I grew up there. So, I got to really kind of focus on the sub culture of the state police." While Jack Nicholson did not speak to reporters on the red carpet, he attracted a lot of attention as even Alec Baldwin stopped mid-speech to take a look at the actor passing behind him. This is Nicholson's first villainous role since 2001. After the tragedy of 9/11 which is reported to have moved him deeply, he had made a conscious decision to only do comedies for a while. Nicholson's performance in the film is already receiving rave reviews. Also in attendance were The Rolling Stones' Mick Jagger, U2's Bono and The Edge and singer Billy Joel who said that that Scorsese has a "kind of a great sense" of the topic he's exploring in the film and that his taste in music is "impeccable." "The Departed" opens across the United States on October