The 1964 title fight in which Cassius Clay defeated Sonny Liston was the kind boxing lives for — a hotshot young pretender, the odds spun upside down, a new era in six rounds. Yet in One Night in Miami, this is just the prelude. A different heavyweight drama awaits.

The date is February 25; the new champ will soon change his name to Muhammad Ali. Tonight, however, as played by Eli Goree, he arrives alone at his victory party, thrown in a motel room by spiritual adviser Malcolm X (Kingsley Ben-Adir). The celebration will also include soul grandee Sam Cooke (Leslie Odom Jr) and American football star Jim Brown (Aldis Hodge). “You mean no one else is coming?” Brown asks, nonplussed. He assumed there might be women guests. Such is the risk when your real host is a screenwriter, laying claim to your evening half a century later.

Between then and now, in 1985, film-maker Nicolas Roeg adapted the stage play Insignificance, bringing together Marilyn Monroe, Joe DiMaggio, Albert Einstein and Joseph McCarthy in a New York hotel suite. It was a cinematic parlour game, a whimsical “what if”. Now, director Regina King riffs again on imagined conversations between historical giants, directing a script reworked by playwright Kemp Powers from his own source material. But this counterfactual is not so contrary to the facts. The principals were actual friends; Clay really did join Malcolm at Miami’s Hampton House Motel to celebrate his triumph. The record even extends to the champion’s taste in post-fight indulgence, referenced here when Malcolm insists his faith won’t stop him showing his guests a good time. He duly produces two tubs of ice cream. (Both vanilla.)

Here in 2021, the film speaks to progress in the film industry at least. Even in the recent past, it is easy to imagine King being invited by producers (if they hired a black woman director at all) to discreetly take aim at an audience unfamiliar with the landmarks of the civil rights era. Now, when these black American icons talk among themselves, they do not have to spend their night explaining to each other that segregation is an evil. Instead, the film gets to the nub of what it feels like to succeed in a system rigged against you. The four-sided back-and-forths simmer with admissions of inner conflict. Outer conflict too. King draws out the friction between Cooke and Malcolm, the seemingly apolitical Mr Soul and the minister from the streets. The action bristles. The cast are on point.

The script doesn’t always make life easy for King. The focus on Cooke and Malcolm is understandable. (Each would be dead inside a year.) Yet by comparison Brown and — more glaringly — Clay/Ali are left as sketches. Still, King deftly navigates another pitfall, a set-up of four men in a single room that might have been designed to read as filmed theatre. A virtue is made of the confined space, the result a masterclass of group dynamics, mirroring a time when even the most famous black American might move freely in here but not over there.

The result is a celebration with jagged edges, history alive with contemporary echoes. “A Change Is Gonna Come”, Cooke sings. This bright, insightful film lets us decide for ourselves how much is unarrived.

★★★★☆

On Amazon Prime from January 15