Like Spike Lee’s Malcolm X (1992), this moving biopic about the slain gay-rights activist Harvey Milk is not only the story of a political leader but a political event in its own right, introducing mainstream moviegoers to a martyred hero and implicitly championing his ideals. Known in San Francisco as the Mayor of Castro Street, Milk pulled off an impressive balancing act in the mid-70s: though he worked tirelessly for gay rights, he also assembled an unlikely power base of gays, hippies, seniors, union members, and small-business owners that catapulted him to elective office on the city’s board of supervisors. Sean Penn gives a meticulously detailed performance as the cagey and charismatic pol, but credit should also go to Dustin Lance Black, whose script squarely locates Milk at the center of his community, his city, and his cause. Gus Van Sant directed. R, 128 min.