“I was born in an area called the plots,” says Paul Nsangu. “In 1989, my father died.” Though his mother then moved the family to another area in order to find work, they continued to struggle. “In 1996,” he goes on, “We lost our mother, and after my mother died, my siblings started dying, one after the other.” Describing his many years of losing people and ongoing dread, Nsangu sits quietly. When the camera pulls back from the closeup on his gaunt face, his bright green socks form sharp spots of color against the dry, burnt orange wall behind him. “What led me to get myself tested,” he says, “was the pain I was experiencing.”

When he was tested, Nsangu learned what he didn’t want to know. Like other members of his family, he was afflicted with HIV. Recalling the moment he learned his status—and apparently, his fate—he slumps in his chair, so thin and frail he seems unable to bear the weight of what he knows.

When Nsangu appears again in The Lazarus Effect, he is transformed. His cheeks are filled out, his eyes are bright, and he is riding a bright green bicycle. In motion, he also smiles. “I am better.” He says, “helping out with chores, going to the market for groceries.” He can now imagine a life with his wife: “I love her because I know she is a strong woman,” he asserts. “We will always be committed to each other.”

Paul Nsangu is alive now, just months after the first images were taken, because he is on a program of Antiretroviral (ARV) drugs, which block HIV’s attack on the immune system. The film offers dramatic numbers: some 20 million people in Africa have died of HIV/AIDS. Now, Nsangu’s remarkable improvement is matched in Lance Bangs’ documentary by similar changes in other subjects, like the young mother Concillia Muhau. When she first appears, Muhau’s condition is heartbreaking: barely able to lift her head, she slumps in a chair, poking through her bag for her pill bottles, just about to begin the regime that will so profoundly affect her energy and outlook. “The way I was feeling in May,” she submits mere months later, “It was like I was already dead.” Now, she is looking forward to watching her three-year-old daughter grow up.

“You’d see the confidence coming back in her,” says Concillia’s peer counselor Constance Mudenda. “She’s got a strength, the force inside her. She can go for a walk without getting dizzy.” Mudenda’s own story forms a center for the film, as she recalls losing her three children to HIV/AIDS. During the ‘90s, when they died, she says tearfully, ARVs were not available. “All I knew was, I go for a test and sit back and wait for death.” Now, Connie is on a regimen of life-saving ARVs, first developed in 1987, but for years too expensive for most Africans to imagine taking. In 2003, Bill Clinton and a coalition of activists convinced the drugs’ manufacturers to reduce the costs in developing countries (the bottom line still holds for those companies: patients must take the drugs for the rest of their lives). Just eight years ago, the number of Africans on ARVs was somewhere around 50,000. Today, the number is 1.34 million.

The film—premiering 24 May on HBO, Channel 4 (UK), and YouTube—doesn’t make explicit the funding mechanisms, though the (Red) campaign is a major source.  Instead, Bangs focuses on effects: Connie describes her work with clients out of the Kinyinya Health Center, outside Kigali, Rwanda. She makes sure they hold to their own medication schedules. The documentary illustrates the seeming miraculous effects of ARVs, showcasing the metamorphosis of 11-year-old Bwalya Liteta: once an emaciated child (just 24 pounds) in a pink and yellow sweater, she’s now back among her friends: “I’m happy because I got better,” she smiles broadly, “And started going back to school.”