Mr. Gast couldn’t even get to grips with the 300,000 feet of footage he’d been shooting. The London-based company, which King said would fund the project, turned out to be backing a Shell company in the Cayman Islands owned by Liberian Treasury Secretary Stephen Tolbert. Mr Gast flew to Liberia to arrange more money, but before they could make a deal, Mr Tolbert died in a plane crash.

Mr. Gast’s attorney David Sonenberg sued in a UK court, and after a year, Mr. Gast had his film and hours and hours of audio piled up in the bedrooms and hallways of his apartment on the Upper West Side of Manhattan.

What he didn’t have was money, so he took on a number of side projects. At one point the Hells Angels hired him to make a film that would counter their reputation as a violent criminal – though they undercut their own case when several of them beat up Mr. Gast (without seriously injuring him) for refusing to give them the to give editorial control. (The movie “Hells Angels Forever” was popular.)

Not all of Mr. Gast’s monetary efforts have been film-related or legal. One night in June 1979, he and at least four other men were waiting at an airport near Charleston, West Virginia, for a plane carrying about 10 tons of marijuana that they smuggled out of Colombia. But the plane crashed on landing and spilled its contents down a slope. Mr. Gast was arrested, found guilty, and fined $ 10,000 and given a five-year suspended sentence.

In 1989, after years of struggling, Mr. Gast reunited with Mr. Sonenberg, who had since become a successful music manager. Mr. Gast persuaded him to take over the rest of the production process and even let him use a room in his Manhattan townhouse as a studio.

Mr. Gast was still keen to focus the film on the festival. But one day one of Mr. Sonenberg’s clients, hip-hop star Wyclef Jean, was in the studio when Mr. Gast was editing a clip of Ali. Mr. Jean was delighted and asked to see more and more of the footage.