Having spent much of the new millennium wandering the indie wilderness with dream-like ruminations on fallen rock stars (Last Days) and dangerously disaffected youth (Paranoid Park, Elephant), Gus Van Sant makes a temporary return to conventional storytelling with Milk, his beautiful and powerfully affecting tribute to slain gay rights leader Harvey Milk.

Milk, of course, was more than an activist. As the first openly gay politician elected to public office in America, the self-appointed Mayor of Castro Street became the none-too-reluctant face of a movement after moving to The City in 1972. Van Sant’s biopic traces his career from its somewhat humble beginnings – Milk opened a camera shop in the Castro shortly after moving to the Bay Area from his native New York – to its agonizing conclusion in his City Hall office.

Although Milk’s rise to prominence may have seemed disturbingly swift to those unaccustomed or hostile to the idea of gay man in office – or, for that matter, out of the closet – he and longtime partner Scott Smith (James Franco) endured a series of unsuccessful campaigns before Milk landed on the San Francisco Board of Supervisors in 1977.

He would serve there for nearly a year before onetime colleague Dan White murdered him and Mayor George Moscone, prematurely ending the life of a man who, perhaps most famously, led the triumphant campaign against Proposition 6, which would have banned gays and their supporters from teaching in California schools.

While Milk dutifully portrays its titular hero as a courageous, groundbreaking activist, it refuses to sugarcoat his brand of shrewd, take-no-prisoners politics. Milk himself would argue that the end justified the means, and rightly so. But there was a slightly fickle, self-serving aspect to his approach that Van Sant and screenwriter Dustin Lance Black (HBO’s Big Love) do not ignore.

Van Sant treats Milk like a traditional biopic, but, as with Elephant and Paranoid Park, there is no concession to melodrama, nor a moment wasted. He presents his story with an unflinching eye on the factual timeline of Milk’s days in San Francisco, right down to the moment of jarring violence that ended his life. This is a movie that could have been maudlin or hagiographic in the hands of a lesser director, but Van Sant’s minimalist approach serves the material well.

For Sean Penn, who plays Milk, there will be much clamoring for an Oscar, and deservedly so. Penn seems less an impersonator of the former city supervisor than a vigorous embodiment. When he’s not railing against his adversaries – White, California Assemblyman John Briggs and anti-gay crusader Anita Bryant among them – there is a tenderness, an endearing sense of humanity in his performance that transcends even the force of his speeches.