San Francisco's Zodiac killer is, like Jack the Ripper, something of a legend. In many ways, he is the archetype of the cinematic mad genius psychopath, fictional characters like Hannibal Lecter, John Doe and Mitch Leary probably not even existing if he hadn't started writing letters to Bay Area newspapers in the summer of 1969.

David Fincher, no stranger to serial killers thanks to the success of Se7en, brings the story of this infamous unsolved mystery to life in the new crime drama Zodiac. To call it the first great film of 2007 would be an understatement. To say it is one of the great procedural thrillers, in the same league as Call Northside 777, M, Panic in the Streets, Rififi, The Day of the Jackal, All the President's Men and Prince of the City, of all time wouldn't just be fitting, it would also be an undeniable fact.

Without a doubt, a filmmaker has not made a flick within in this genre as good as this one in eons. The picture is an instant classic, as absorbing and as mesmerizing as anything I have ever seen in my short career as a professional film critic. It is better than Oscar-winner The Departed, probably better than any of the five features up for the Academy Award for Best Picture last weekend, and the only real tragedy here is that now, with a March release, the chances of this one being remembered same time next year are probably somewhere between slim and none.

Based on the book by former San Francisco Chronicle political cartoonist Robert Graysmith and working from a script by James Vanderbilt (a huge improvement over dreck like Darkness Falls, The Rundown and Basic), the movie is a crackerjack example of filmmaking at its finest. Fincher has eschewed many of his usual visual shenanigans and instead gives his feature a documentary-like verisimilitude that's astonishing. The whole thing is presented with stone-cold authenticity, and much like I felt after watching Fargo in February of 1996 if I see a better film this year I will be hugely surprised.

Of course, those expecting the usual Fincher thrills and chills or the gore and splatter he's been associated with in previous efforts like Fight Club, The Game, Alien 3 or Panic Room better look for their entertainment elsewhere. This is a police procedural infatuated, not so much with the killer himself, but with the toll catching him, or better yet not catching, ultimately takes on four of the men most intimately connected with the job. It is their story which forms the dramatic base, their descent into frustratingly laborious no-win hell making this a masterpiece, and the longer the film went on the more I could feel my own soul twisting, turning and shivering out there in the cold unceasing wind right along with them.

Those men; lead San Francisco detective Dave Toschi (Mark Ruffalo), his partner William Armstrong (Anthony Edwards), Chronicle star reporter Paul Avery (Robert Downey, Jr.) and the aforementioned Graysmith (Jake Gyllenhaal); see their marriages ruined, the careers stalled and their family lives destroyed by this case. Obsession overwhelmed all of them, the pursuit of a killer too good at hiding his tracks, and the only evidence available to catch him too circumstantial to use, enough to drive each man insane.

Each actor does remarkable work. Downey, in particular, shines as mad hatter Avery, each level of the mania overtaking exemplified by the more erratic and self-destructive he becomes. He is matched by both Edwards (showcasing subtlety he was never allowed while on E.R.) and Ruffalo, the latter bringing to life a real-life cop who has been the basis for classic cinematic interpretations (Bullet, Dirty Harry and so on) for over three decades with superbly moving gusto.

In many ways, though, this whole thing belongs to Gyllenhaal. As good as his Oscar-nominated work in Brokeback Mountain was, this is the kind of performance which really sneaks up on you the longer the film goes on. At first he is just a mousy, somewhat nosey fly on the wall, insinuating himself into the newspaper's investigation mainly because the ciphers the killer is using catch his inquisitive eye. But the web spinning around him soon becomes all-encompassing, the actor making Graysmith's devotion to the case a thing both tragic and laudatory all at once.

Fincher has assembled a crackerjack team of craftsmen to help him bring this story to the screen. Cinematographer Harris Savides (Last Days) shoots with a gritty 1970's-style urgency, while Donald Graham Burt's (Donnie Brasco) production design is so lived-in you could almost believe the filmmakers went back in time and shot their picture right along with the actual events. Best of all is David Shire's (an Oscar-winner for Norma Rae) score, adding just the right touch of pulsating urgency and ranking right up there with the acclaimed composer's music for similar works like Francis Ford Coppola's The Conversation and Alan J. Pakula's All the President's Men.

Fincher has made groundbreaking and classic entertainment before. For both better and worse, Se7en changed the way we look at serial killer thrillers forever, while Fight Club probably still ranks as one of the most under appreciated yet most influential pulp entertainments of the last decade. He's a filmmaker that takes chances and pushes boundaries, doing it all usually without losing touch with the stories and characters making this innovation noteworthy.

While this one doesn’t necessarily break ground we haven't seen before, that doesn’t make it any less a masterpiece. Zodiac soars, so enthralling and intoxicating even at more than 150 minutes it feels like it is over just as soon as it begins. The film is a remarkable achievement, and for audiences so used to the ordinary watching something as fantastic as this might just be a revelation.

Film Rating: êêêê  (out of 4)