One of the best films of the year, Margaret Brown’s “Descendant” is, strictly speaking, about the discovery of the Clotilda, the last known slave ship.

After it was used to illegally kidnap and enslave more than 100 Africans, the 90-foot-long schooner was sunk near Mobile, Alabama, around 1860, decades after the international slave trade was outlawed. Until recently, it laid unfound somewhere in the muddy waters of the Mobile River, a lost, 160-year-old crime scene.

But “Descendant,” a prize-winner at the Sundance Film Festival, is exponentially more than an account of finding the Clotilda in 2019. Brown roves across the land, crowding her film with a wide spectrum of voices — community leaders, direct descendants from the Clotilda, passed-down accounts — for a living oral history that reckons with the long shadow of slavery. “I could care less about the ship,” says Joycelyn Davis, one of the film’s many vibrant, thoughtful subjects and a resident of Africatown, the Mobile hamlet founded by the Clotilda’s West Africans.

Modern-day Africatown is, itself, evidence of how systematic racism can operate. With the city’s highest industrial zoning regulations, Africatown has long been surrounded by factories and refineries, leading to pollution and high local cancer rates. For “Descendant,” it’s a powerful illustration of how past and present perpetually intermingle in America.

“Descendant,” which Friday opens in select theaters and debuts on Netflix, is in many ways about storytelling as a form of resistance. Those that came on the Clotilda were warned not to tell anyone of their trafficking. The story went undocumented in history books. Instead, it was passed by word of mouth as local lore kept alive by descendants. Emmett Lewis, a particularly soulful descendant of Africatown founder Cudjo Lewis, describes it as “a ghost story” told to him by his father, and one he tells his young daughters.

For many, any clarity about the Clotilda is a way of adding definition to a severed heritage. One woman compares it to an adopted child searching for a parent. Among those who have learned that they’re a Clotilda descendant is Ahmir “Questlove” Thompson, an executive producer on the film.

At the same time, the ship’s finding raises other questions of justice and of reparations. For many of the descendants, it’s not a theoretical question. The slave-trafficking financier of the Clotilda, Timothy Meaher, may have died more than a century ago, but his family is still a wealthy landowner in the area. The Meaher name adorns a local park.

There are few certain answers supplied by “Descendant,” a film that carries the banner of Barack and Michelle Obama’s production company, Higher Ground. But there is a searching, ruminative dialogue running throughout the film. Brown and editors Michael Bloch and Geoffrey Richman beautifully weave together disparate voices into a meditative chorus.

It’s not just the living, either. Kern Jackson, a kindly folklorist and a central figure in the effort, plays a VHS tape of Mable Dennison, a descendant who wrote a biographical memoir of her grandfather, James Dennison, instructing others about their heritage. Brown also has many of the descendants read from Zora Neale Hurston’s “Barracoon,” a book based on her interviews in 1927 with Cudjo Lewis. It was surfaced only in 2018 by the author Alice Walker.

“The only fear,” Emmett Lewis says in the film’s final words, “is for my people’s story not to be told.”

“Descendant,” a Netflix release, is rated PG by the Motion Picture Association of America for thematic material, brief language and smoking images. Running time: 109 minutes. Four stars out of four.