The surreal filmic world of director Terry Gilliam, Monty Python's ex-animator, exists in a visual jumble of monochrome settings smudged with dirt and paranoia. His threatening settings, from the totalitarian business offices of his absurdist masterpiec e "Brazil" to the trash piles of a homeless wanderer in "The Fisher King," surround the viewer through wide angle lenses and an offsetting mix of fantasy and reality. His films incorporate fantastical visions so easily, it's often difficult to separate fa ntasy from reality, which, of course, is his whole point.

His latest is "Twelve Monkeys," a science fiction mindbender centering on James Cole, a prisoner from the 21st century who lives underground with the last remaining humans, beneath a frigid and decaying Philadelphia leftover from a cataclysmic plague that wiped out 99 percent of the world's population. He's recruited by menacing scientists and sent back in time to locate the source of the virus that ravaged the world in 1996.

The intriguing story, by "Blade Runner" scribe David Peoples and his wife, offers a refreshing take on the time travel paradoxes thrown about in science fiction cinema. Instead of changing the past and playing with changes in the future, the scientists de cide that history cannot be changed and it's only their mission to obtain information that will allow them to develop a vaccine. They don't want to play with chronological chaos, they only want to save their present.

But time travel is a delicate sport and Cole arrives early in 1990 to a hostile world who'd rather believe he's a raving, violent lunatic than help him piece together the mystery of mankind's impending doom. Cole is sent to a mental ward and the movie buf fets the "rational" explanations of his doctors with his jumps back and forth through time and his growing confusion as to what is real and what is actually imagined constructions of his psyche. Cole begins to believe he is imagining his predicament as ee rie voices echo through walls and his natural propensity for violence results in constant beatings.

"Twelve Monkeys," as with much of Gilliam's work, is the sort of transcendental fiction usually reserved for science fiction literature rather than the movies. As technology has increased and Hollywood's propensity for visual spectacle begets more startli ng visions, the history of science fiction cinema has been primarily one of gadgets and special effects. But "Twelve Monkeys" is a film that refreshingly transcends those boundaries and explores the sort of psychological conundrums New Wave science fictio n authors like Philip K. Dick or J. G. Ballard popularized in the '60s.

The movie is a stunning combination of surreal imagery, gritty urban reality, darkened humor, and enough circular logic to keep viewers thinking about it for days afterward. The title comes from the mysterious terrorist group called The Army of the Twelv e Monkeys who are linked to the original viral outbreak. The movie leaves clues about the group as Cole discovers their crimson graffiti sprayed on buildings and the film's haunting accordion rhythms drift in and out. Gilliam composes his shots using tilt ed frames, sending his camera slowly spiraling through locations with dizzy vulnerability.

"Twelve Monkeys" is consistently enjoyable and a large part of it's success is due to its imaginative use of Hollywood stars. Audiences hoping to experience a Bruce Willis action flick will no doubt be disappointed, as Willis stumbles through the film as a ravaged, drooling madman bent on escaping the trials of his mind. It's an impressive performance, full of anger and determination, but it's nearly overshadowed by Brad Pitt as a neurotic mental patient who snaps his arms in spastic frustration while esp ousing intellectual mumbo jumbo. Pitt provides much of the film's twisted humor as he upsets an entire mental ward, gives a meaningless discourse on a balcony during a chaotic fight scene, and continually treads a fine line between functional sanity and u ncontrollable hyperactivity.

"Twelve Monkeys" is an intelligent addition to the genre with its experimental look and provocative narrative. It's the type of movie that provokes long-winded discussions and entices viewers to return for a second visit. Though Gilliam was a member of th e Monty Python troupe, he's an American and quite an anomaly in Hollywood. His personal vision and artist's eye for powerful visuals has provided unforgettable moments in recent years. "Twelve Monkeys" is no exception.