What links the Holocaust, India’s class system and slavery? That’s what African-American journalist Isabel Wilkerson set out to discover in her sensational 2020 book Caste: The Origins Of Our Discontents. In this appropriately ambitious and desperately moving take on Wilkerson’s story, Ava DuVernay shows how the writer came to her conclusions, doing so amid great personal turmoil.

When we meet Isabel (Aunjanue Ellis-Taylor), she is leading what appears to be a charmed life, featuring swanky galas, powerful public speeches and domestic bliss. Although her elderly mother Ruby (Emily Yancy) is ailing, the pair share a touching bond, and Isabel is well supported in her efforts to care for Ruby by her devoted husband Brett (Jon Bernthal). A Pulitzer Prize-winning journalist and acclaimed author, Isabel is being courted by an editor who wants her to weigh in on the tragic shooting of teenager Trayvon Martin. She’s initially reluctant, due to concerns for her mother’s health, but when personal tragedy strips away her distractions, Isabel seeks solace in work.

Origin follows this remarkable woman as she challenges the idea that racism is the driving force behind America’s persistent mistreatment of its black population, instead attributing it to the concept of caste: the phenomenon of putting one group above another in a hierarchy, regardless of racial origin. Isabel travels to Germany, where she learns how the Nazis used US race laws to figure out how to brand Jews as inferior, with the ultimate goal of exterminating them. Later, she goes to India and hears about the abysmal treatment of the Dalits and parallels with the subjugation of black Americans, discovering that Martin Luther King Jr and revered Dalit scholar Bhimrao Ambedkar had made this connection before her. The film also brings to life some shameful stories from history which crystalise the suffering.

DuVernay has form in making us think and care about prejudice and systemic oppression. Selma was a hugely stirring civil-rights drama, mini-series When They See Us shone a light on terrible injustices stemming from the Central Park jogger case, while her documentary 13th delivered an illuminating look at the US prison-industrial complex, persuasively arguing that slavery is still alive and kicking today.

Here, the director builds on those strengths and shows admirable curiosity as she crafts a film that contemplates a wider explanation for America’s wrongs and acts as a testament to the resilience of the human spirit. Watching Isabel strive to uncover the roots of our divisions while battling sometimes all-consuming grief is as gripping as any thriller; fluid, Terrence Malick-evoking photography and gorgeous fantasy sequences from cinematographer Matthew J Lloyd illustrate how our heroine becomes lost in the fog of agony, only to be swept back up by the strength of her ideas.

Origin is a film that feels exhilaratingly intelligent and wholly refreshing. Cinematic takes on creative or cerebral journeys, however imaginative, have commonly focused on white people, and almost always men (think Adaptation, Le Mépris, The Theory Of Everything), while it’s also notable that DuVernay has chosen to highlight such a recent text (a book you’ll want to rush out and read).

Oscar-nominated for her role in 2021’s King Richard, Ellis-Taylor does full justice to a beautifully written character, playing a woman brought devastatingly low who still reaches the heights of her intellectual potential. The sensitivity she shows here really is exquisite and she’s well flanked by Bernthal and a scene-stealing Niecy Nash-Betts as Isabel’s straight-talking cousin, Marion. Meanwhile, actors of the calibre of Vera Farmiga, Audra McDonald, Connie Nielsen and Nick Offerman all appear in support.

Films dealing in big, challenging theories often struggle to pack a punch, with characters sounding like mouthpieces for the concepts in question, rather than human beings in all their strength and fallibility. That DuVernay manages to draw together multiple stories and keep Origin’s intellectual and emotional plates spinning is astonishing, as is her ability to impart ideas with the power to transform and unite. In a world that seems more fractured than ever, where people compete over injustices rather than seeking an end to all our suffering, this film matters.

Origin, GFT, Glasgow, Saturday 2, Tuesday 5 March, as part of Glasgow Film Festival; in cinemas from Friday 8 March.