We Were Here shows that a situation you think you know can be something you haven't known at all. That is the surprise, and the power, of this unexpected film, screening next week as part of the One World Film Festival.

An extraordinarily moving examination of how the AIDS epidemic devastated yet transformed San Francisco's gay community, this clear-eyed and soulful documentary from 2011 brings us inside the contagion in a way that is so intimate, so personal, you feel as if you're hearing about these catastrophic events for the first time.

It's not surprising that We Were Here comes from producer-director David Weissman and editor/co-director Bill Weber, the team responsible for 2002's The Cockettes, one of the few documentaries about San Francisco in the deliriously countercultural 1960s that allows you to experience what it felt like to be there.

Rather than bring in a variety of experts, We Were Here has chosen to interview extensively a handful of candid and articulate survivors who experienced the crisis and, sometimes alone among all their friends, lived to tell the tale.

Death is always present in their stories, "an avalanche of death" in artist Daniel Goldstein's words, death to such a staggering extent that the film seems like a real-life Contagion, albeit one filled with much more heart and soul.

For as much as the devastation, what We Were Here also emphasizes is the way San Francisco's gay community rose to the challenge, turning itself from a group singled out for its hedonism to one celebrated for its tenacious will to survive and a breadth of compassion that surprised everyone involved.

We Were Here starts not with the bad times but with the Castro Street-centered party atmosphere that began in the mid-1970s. The film's subjects — Goldstein, florist Guy Clark, political activist Paul Boneberg, AIDS counselor Ed Wolf and nurse Eileen Glutzer — are delighted to reminisce about how good the good times really were.

Then, in 1981, came the first hints of an end to paradise. Wolf remembers seeing a small hand-lettered sign in the window of a Castro pharmacy that accompanied Polaroids of a man with big purple splotches on his body. "Watch out guys," he remembers the sign reading, "there's something out there."

In fact, the film tells us, the virus that causes AIDS probably arrived in San Francisco in 1976 and had infected 20 percent of the gay population there by 1981, a rate that rose to 50 percent by the time a test for the disease was in use.

We Were Here follows the entire course of the contagion, from its beginnings as a mysterious "gay cancer" to how 15,548 people in the city came to die before the disease was brought under control in the mid-1990s. We hear story after flabbergasting story about research projects where no one survived, about passionate kisses at death's door, about a father more upset that his son was gay than that he was dying. "I don't need to be here," Goldstein says, recounting his suicidal state after a particularly horrifying experience. "I thought I was going to lose my mind."

By contrast Wolf, who admits to going against the stereotype by being a gay man who "was terrible at anonymous sex," found his vocation when the epidemic started and joined the Shanti Project, which provided human-services assistance to people with AIDS. "My way of being with gay men," he says, still not believing it, "suddenly was perfect."

Because of the nature of the story it tells, We Were Here can be difficult to watch at times. Photographs and movie footage of the infected and the dying make it clear exactly how ruthless the disease could be.

Yet experiencing that despair also allows us to understand how remarkable the resilience of the San Francisco community was. We hear from Boneberg about political activism by dying people, determined to help those still alive, and about the resolve of nurse Glutzer. "I didn't choose it, it chose me," she remembers explaining to her mother. "I couldn't turn my back to it."

Because of the selflessness so much illness brought out in so many people, We Were Here is easily more heartening than depressing, more uplifting than wrenching. "How did I get through it?" Goldstein asks rhetorically. "I don't know, you just do it. It's not heroic."

Viewers of this enriching film probably will differ about that.

One World Film Festival: 'We Were Here'

★★★★★

No MPAA rating. The Film Collaborative. 1:30.

When: 5 and 7:30 p.m. March 7

Where: Kentucky Theatre, 214 E. Main St.

Admission: Free

Learn more: (859) 266-6073, Oneworldfilmfestival.org