“In this place, much that happened to me in my early life was sorted out.” Harry Belafonte leads a camera through the hallway of a Harlem apartment building, the crew’s light bouncing harshly off the walls. “I met people, here,” he says, walking inside a small and empty room, an old radiator huddled against the wall, a bucket of paint on the stripped wood floor.

Belafonte looks pensive as the wide-angle lens turns around him in Sing Your Song, premiering 17 October on HBO. Susanne Rostock’s helps you to imagine what he might be remembering with a montage of images showing people in trouble—injured and bloodied, unhappy and hungry, pursued by police or adrift in floodwaters, in New York City and in Capetown, South Africa, behind bars and marching in the street. The sequence flashes quickly, the rush of pain and resilience intimating both how much work Belafonte has done over the years as an activist and also, how much work remains to be done.

And this is the insistent focus of the film, which uses its subject’s celebrity as a means to showcase a range of causes and concerns, each urgent in its own way, and all ongoing. Belafonte says that he was moved to make the film in part because he wants this particular part of his story told. When his friend Marlon Brando died in 2004, “he took with him stories of all the remarkable things he had done. That upset me,” Belfonte tells USA Today. So I decided to take a camera and see how many others were left from my generation.”

And so Sing Your Song‘s attention to activism mirrors Belafonte’s own. As he recalls here, his inclination to activism was ignited early, as a boy whose mother worked as a domestic, and who sent him and his brother to live with relatives in Jamaica: “Almost all the songs that I later came to sing,” he says, “were songs that I heard among the people, the peasants, my family, at the time.” The film shows photos of Jamaican workers, children and the shoreline, as he credits his mother for making him believe “There was nothing in life that I could not aspire to.”

His aspirations were soon shaped in a particular way, when he attended a show at the American Negro Theater. “It transfixed me,” he says, “It was a place of social truth, a place of power. It carried thoughts that could influence people profoundly.” Belafonte was soon in classes with Marlon Brando and Walter Matthau, he says, and, even as he felt he was being routed along a path to become a “jazz singer,” he resisted, finding inspiration instead in Huddie Ledbetter (“He sang songs in a way that was absolutely magical for me,” he says) and Paul Robeson. As the film cuts to that most iconic of Paul Robeson moments—singing “Ol’ Man River” in the movie Showboat, the camera craning over and around him—Belafonte tries to put the effect into words: “His strength, his power, the way in which he used his life as an artist, had extraordinary influence on me.”

Sing Your Song doesn’t specify the obstacles Robeson confronted, but those notorious official efforts to suppress his “song”—the blacklisting, the FBI and CIA surveillance, and the revocation of his US passport in 1950—hover over Belafonte’s story, along with Robeson’s advice to him: “Get them to sing your song, and they’ll want to know who you are.” Belafonte chose songs that demonstrated his own and others’ backgrounds, from gospel and calypso to spirituals and folk songs. He developed a public profile, in part by touring with Marge and Gower in “Three for Tonight” in 1955. He and Marge Champion both recall the devastating effects of that tour: he was coming from New York and she from California, and neither was prepared for the elaborate segregation of the US South: Belafonte was not allowed to eat or sleep with his white fellow players, or even enter the same doorway.

The experience only made Belafonte more determined to resist oppressions, those affecting him directly and also those affecting populations who didn’t have the chance to speak out as he did. During the late ‘50s and into the 1960s, as his musical star rose (the film briefly notes a few hits, with clips of “Who’s Gonna Be Your Man?” or “The Banana Boat Song [Day-O]”), Belafonte also developed a Hollywood career, in movies including Carmen Jones and The World the Flesh and the Devil (in which his relationship with Inger Stevens was changed to accommodate “Southern viewers”).

Recalling Robeson and coming to understand his own potential influence, Belafonte aligned himself with Martin Luther King, Jr., worked with SNCC during Freedom Summer, and also used his appearances on TV shows to facilitate social and political changes. He helped to integrate shows hosted by Ed Sullivan (who introduces him during one appearance as “the great American artist and one of the greatest artists of the world”), Dinah Shore, Merv Griffin, and Steve Allen. He interviewed John F. Kennedy for TV, appeared on Nat King Cole’s show, and hosted his own special, featuring traditional songs and highlighting black folklore.

When this show was a success, the sponsor, Revlon, ordered five more: clips here show what he and his colleagues produced, with numbers ranging from spirituals and children’s songs (on an abstract city-set, with kids jumping rope) to Mexican folk songs and “Hava Nagila.” As energetic and ambitious as this international effort was, the sponsor determined that the mixed race performers were not permissible, however, and directed Belafonte to appear only with other black singers and dancers. He refused, and Revlon pulled the shows.

As popular as Belafonte was, and as much as “white teenyboppers” would swoon over him (his daughter Adrienne remembers being mystified by this effect), he stuck to his political principles: Tommy Smothers credits him with helping to get his and his brother’s variety show cancelled, when Belafonte shot a segment where he was singing “a Calypso medley against backdrop” of footage from the 1968 Democratic convention. As you look at some of this performance now, Smothers notes that CBS pulled it and inserted instead “a political commercial for Richard Nixon.”

This sort of context—commercial media’s cowardice and bottom-lining—remains in place to this day, of course. And as Belafonte embodies the idea that art and politics always mix, no matter the era, he also continues to act on that belief.