The film is only an hour long and you’ve probably never heard of many of the people in it. And it has no real “plot.”

But you’ll find it to be one of the most joyful films you’ve seen this century. Or ever.

It’s called “No Maps On My Taps” and it’s a mini-documentary of a time in the 1930s when black tap dancers were making a big noise at the Apollo Theater and Small’s Paradise in Harlem.

Originally made in 1978, when many of the dancers were still alive, the film includes interviews, rich reminiscences, and clips from some of their movies and stage appearances.

The narrator is a dancer called Harold “Sandman” Sims, whose special innovation was dancing on a stage lightly dusted with sand that produced a soft, squishy sound to his taps. He is joined by two of his contemporaries: “Bunny” Briggs and Chuck Green. They start the film by dancing together.

Sims, who began dancing when he was four years old, was considered “clumsy” by his older brothers and sisters, who were all dancers. And so he began his career by competing with them. He grew up, he says, feeling like The Ugly Duckling, but he became “a beautiful swan” very quickly and by the time he was six he was telling one of his brothers, “Here, lemme show you how to do it.”

Competition was what drove these dancers, but they adhered to the advice of their more experienced elders: “Do your thing, but don’t do what somebody else is doing. Always do what you’re able to do.”

They challenged and tried to outdo each other, but they considered themselves a “competitive fraternity.” And when they played a theater like the Apollo they would spend the time, when they weren’t onstage, holding private dance contests in the alley behind the theater.

Bunny Briggs tells a story that still brought a tear to his eyes all these years later. When he was six years old he was spotted by the man whom they all considered the greatest dancer of them all — Bill “Bojangles” Robinson. Robinson was so impressed with the little boy’s skill that he went to Bunny’s mother and asked permission to take the boy on the road with him and make him his protégé. She, of course, was overwhelmed by the offer and agreed immediately. But Bunny’s aunt, who was a dancer in the chorus, talked her out of it and in the end Bunny’s mother changed her mind.

Robinson himself was shown in this film dancing in clips from his movies, including the iconic scene from 1935 in “The Little Colonel” in which he and the six-year-old Shirley Temple tap-danced their way up a flight of stairs.

Another film clip shows John Bubbles in his role of Sporting Life in “Porgy and Bess.” And in an impromptu interview on the street Sims asks an old-time dancer named Candy why he took up dancing and was told, “There were too many singers and I wanted to break the monotony.” Candy acknowledged that he had never taken lessons, but he had “rhythm and soul” that he picked up on the streets of Harlem.

Sims explains that black kids “had to pick it up on the street” while white kids went to dancing school. “We danced with our hearts and souls, but the white kids danced to the numbers, 1, 2, 3, 4, 5, 6. The difference was like night and day.”

And Bunny Briggs added, “You’re a free man when you jazz dance,” because “nobody can tell you what to do.”

This beautiful film was digitally restored in 2017 by George T. Nierenberg with grants from the National Endowment for the Arts, the Corporation for Public Broadcasting, and the American Film Institute. Lionel Hampton is credited as the original music director, and Milestone Films produced the restored copy.

The film will open at the Laemmle Royal on September 15.