TORONTO - A few years ago, when he was shooting a movie in New Orleans - his directorial debut, Sonny - something mysterious happened to Nicolas Cage. He won't say what it was, except that it frightened and delighted him, and that he was afraid to go back to the city.

"It did sort of change my beliefs and my way of looking at things, looking at life. My philosophy," he said Tuesday. "It all led to an awareness of how I relate to other people and my interest in society, as opposed to my interest in myself. My interest in making a big noise: 'Hey look at me.' I'm trying to go the other way now."

He added, "It's tricky, because I'm in a business that is actively revolving around vanity . . . there's a certain level of arrogance to the whole thing that I'm trying to destroy."

In any event, it was with some trepidation that Cage took a role in Bad Lieutenant: Port of Call New Orleans, Werner Herzog's remake-that's-not-a-remake of Abel Ferrara's 1992 movie with Harvey Keitel as a tormented policeman who broke the law as much as he enforced it. Herzog says he hates the title, rejects the idea that it's a remake, and opposed the notion that the Bad Lieutenant films could become a franchise, moving from city to city (he also has written a manifesto that challenges film academics to find relationships between the two films: "Go for it, losers," he writes.)

Still, he took on the project and approached Cage to star. The film, which had its premiere at the Toronto International Film Festival, was originally set in Detroit but moved to New Orleans for tax reasons and because, as Herzog said, "that's where the bliss of evil has to occur."

Cage said he was so afraid to go back that on the first day of shooting, he forgot his lines. But shooting Bad Lieutenant acted as a catharsis: he said he overcame his fear and also realized that, just like the jazz that was born in New Orleans, so his acting could become an improvisation on a theme.

"I was born in Los Angeles, but you could say on some level I was reborn in New Orleans," he said.

The result - which also includes a scene with imaginary iguanas (Herzog loves throwing animals into his films) and a sequence in which a dead man has to be shot again because his soul is still break-dancing beside his body - is an astonishing black comedy in which Cage gives his best performance since Leaving Las Vegas, the 1995 movie that won him an Academy Award for best actor. Shuffling along with a bad back that makes him bend over and scowl like a particularly mad Richard Nixon, Cage's character snorts endless drugs, gets involved with gamblers, and protects his prostitute girlfriend (Eva Mendes) from the Mafia, all while trying to solve a brutal murder.

It's slightly insane, which is the way Herzog likes it, with Cage as his co-conspirator: in one improvised scene, the Cage character freebases cocaine and launches into a riff on how he once saw a football player leap over a tackler, sprout antlers, and score a touchdown. Cage says the hallucination was told to him by some friends 20 years ago - the friends were on drugs at the time - and it has been with him since then. Herzog's instruction to Cage, when it was time to push the limits of the film, was, "This time you shall turn the pig loose."

The pig is a metaphor; the iguanas were real. There's a scene where Cage's character, stoned on drugs, sees two iguanas that no one else can see. "Werner was very devoted to his iguanas," Cage said, and at one stage, he said if he couldn't have a full three minutes of "iguana time," he would never again make a movie. Cage went to the director and volunteered to have one of his own scenes cut to create the iguana time, but Herzog decided there was room for both.

That's the sort of thing that attracted Cage to the film in the first place.

"I was thrilled," he said of the iguana moment. "That made me happy because I knew then that Werner was working his magic."

His own magic involved fully inhabiting the bad lieutenant. He said that even in his previous movies, such as Face/Off or Vampire's Kiss, "I do like a certain line of energy, of sound and rhythm and movement that goes a little bigger." As in music or painting, he said, "there is no top. There is no top to imagination. You can create new sounds and bigger physical performances once you get rid of that box, that top, and you can liberate yourself, and I encourage other actors to try that as long as it works in the context of the director."

He added that if a performance gets bigger, that doesn't mean it's less honest. The character's drug use allowed him to hit what he calls bigger notes and "way out dance moves." Most important, he said, was the surprise that there could be comedy in a movie called Bad Lieutenant.

Indeed, the very idea that the film could be revisited was part of what appealed to Cage. "I liked the audacity, I liked the bravery of it. I thought it was just a way-out, shocking thing to do." The fact that it was shot in New Orleans was also a big factor: "It could have been a disaster or it could have been something beautiful." Either way, he felt it would help the work.