An Unreasonable Man, Henriette Mantel and Steve Skrovan's compelling documentary about Ralph Nader's career, opens with the biting comments of detractors who blame him for the Democrats' losses in the 2000 and 2004 presidential elections - and in turn unpopular George W. Bush-induced issues. At this early point in the movie, no more data is given: Nader's responsibility for the current state of the country, the filmmakers seem to be saying, is as obvious as the fact that he was never going to win. Then Mantel and Skrovan turn the climate around. Using archival footage and a running commentary by people close to him, they go back to the beginning of the attorney/activist's public career. Prompted by an accident that left a friend of his a paraplegic, Nader's first cause was the design of automobiles. He wrote a book, Unsafe at Any Speed, which largely focused on the Chevrolet Corvair. Thrusting Nader into the spotlight was the weird series of events that followed, including an attempted smear campaign by General Motors. The experience and Nader's newfound fame led him to years of public-safety advocacy, with Newsweek dubbing him "the Consumer Crusader." It's difficult not to think Nader a hero based on this gleaming, intricate biography. You even cheer for him as the film covers his 2000 candidacy, showing snippets of speeches and zealous rallies that suggest he's the fresh air Washington has been lacking. Then, somewhat unsubtly, it's time to flip back to the naysayers (Nader should have known better in 2004) and back again to the supporters (stats prove that he wasn't a factor in Bush's win). Though Mantel and Skrovan's thoroughness - and even balance - are to be commended, it all gets a bit head-spinning toward the end. The documentary is undeniably informative and interesting, and will serve as an adequate crash-course for Nader neophytes. But a film dedicated to a man with a jones for warnings should come with this one: Like Nader himself usually is, it's better to go into An Unreasonable Man already armed with an opinion.