NEW YORK -- Together, they've visited the mean streets of 19th-century New York ([movie id="209977"]"Gangs of New York"[/movie]), soared through the sky via the vision of an unstable multimillionaire ([movie id="238182"]"The Aviator"[/movie]) and investigated the menacing world of Boston organized crime ([movie id="260446"]"The Departed"[/movie]). Arduous undertakings all, but it was the fourth big-screen collaboration between [movieperson id="16710"]Leonardo DiCaprio[/movieperson] and [movieperson id="97888"]Martin Scorsese[/movieperson], the two men revealed to MTV News, that pushed them creatively and personally like never before.

"This was a particularly intense one for the both of us," DiCaprio said on the red carpet of the [article id="1632136"]"Shutter Island" premiere[/article] (opens Friday), their psychological thriller about an investigation at a super-creepy hospital for the criminally insane.

"We always think it's going to be the same, but it wound up going a little further, I think," Scorsese told us. "[Leo] was able to handle it. He's an amazing actor."

So what made the [movie id="371226"]"Shutter Island"[/movie] shoot so much more intense than their previous dramas? Little should be revealed about the new film's plot, which veers into areas of delusions and terrors that leave objective reality up for discussion. Suffice to say that capturing all this on camera forced DiCaprio and Scorsese to explore some sketchy territory.

"It was dream sequences and sequences of [my character's] own past that converged into one and everything sort of overlaps," Leo said. "We kept pushing the intensity of each one of these sequences further and further and it wore on all of us. We had to go to some pretty crazy places."

Travel to those crazy places was the plan all along. "What I liked about it was that it made me rethink constantly how we perceive ourselves and the reality around us. Look at where we are now, it's so surreal," Scorsese said as he gestured toward the flashing lights on the red carpet. "I found it interesting because you can keep peeling away the layers and you get more of a story and more of a story and then maybe you learn a little about yourself."

Check out everything we've got on "Shutter Island."

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