Sean Penn gives one of his most fearless and thrilling performances in "Milk," director Gus Van Sant's recounting of the life and violent death of the first openly gay man to be elected to a significant municipal position in America. The year was 1977, the position was on the San Francisco Board of Supervisors, and the man was Harvey Milk, a disarmingly cheerful but determined gay-rights activist. Milk was a major figure in the battle against social intolerance, but he never lived to see the major changes his modest political triumph helped facilitate. After being sworn into office, he had less than one year to live before being murdered by an unbalanced fellow supervisor.

Van Sant takes up Milk's story in 1970, in New York, where he's a closeted gay man (and a Republican) working for an insurance company. It's his fortieth birthday, and down in a subway station he strikes up a conversation with a younger man named Scott (James Franco), who's friendly, but not especially available. "You're cute," he tells Harvey, "but I don't date guys over forty." Since Harvey comes in just under that particular wire, they return to his apartment and eventually make love.

Scott is surprised that Harvey is still in the closet. He suggests they relocate to San Francisco, where a new gay neighborhood is coming together in the Castro district. The '60s hippie era is definitively dead, but Harvey, flushed with liberation, goes longhair anyway. Now completely out of the closet, he organizes a gay boycott of homophobic businesses. "We can change things," he says, "but we have to start with our neighborhood." Next, he strikes an unlikely alliance with the Teamsters for a gay boycott of the non-unionized Coors beer company, in return for which the Teamsters agree to accept gay truck drivers as members. Now thoroughly hooked on politics, Harvey cuts his hair and takes to wearing three-piece suits. He runs for various offices and keeps losing, but by smaller margins each time. His self-deprecating demeanor is hard to resist: "I know I'm not what you expected," he tells one group of potential straight supporters, "but I left my high heels at home."

Milk is sworn into office in January of 1978, along with another new supervisor named Dan White, a conservative ex-fireman. White is a man of deep and unpredictable dark moods; he seems obscurely conflicted, and Harvey is intrigued: "I think he may be one of us," he tells some friends. Maybe, maybe not. One day in November of 1978, in a spasm of rage at a perceived political injustice, White goes to City Hall with a gun, shoots the mayor, George Moscone, in his office, then seeks out Milk, luring him into another office and shooting him, too. (White served just five years in jail for this double homicide; a year and a half after his release, he committed suicide.)

The most striking thing about Van Sant's film is the carefully muted dignity with which it presents Milk's story, never descending into melodrama or gay-rights boosterism (except at the very end, which perhaps should have been re-thought). Instead, he builds up an intimate portrait of the man through an accretion of simple human details. (He makes little attempt to canonize his subject, either, scrupulously highlighting Milk's distasteful insistence on outing closeted gays, and his unattractive desire to impose his liberal political agenda in every direction.) And in Penn, the director has a near-perfect star: a straight actor capable of playing a gay man without holding back in depicting Milk's mannerisms, but without treading anywhere near gay caricature, either.

Penn receives extraordinary support from the rest of the film's cast. Franco, especially, conveys a luminous affection for the man who'll eventually drive him away in his obsession with politics; Diego Luna is alternately hilarious and heartbreaking as Milk's new boyfriend, the loveably whacked-out Jack Lira; and Emile Hirsch, as a street-cruising Castro kid converted to Milk's political activism, and Alison Pill, as the candidate's pretty but hard-nosed lesbian campaign manager, create fully inhabited, memorable characters. But Penn presides over the movie with complete and unforgettable conviction. When he tells a friend who's asked if it'd be all right to visit him in City Hall that he certainly should, "and wear the tightest jeans possible -- don't blend in," you marvel at the precision of his tone and delivery. He's a wonder to watch.

Don't miss Kurt Loder's review of "Australia," also new in theaters this week.

Check out everything we've got on "Milk."

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