Everyone who loves documentary, who cherishes the Maysles brothers’ legacy, should rush to the Brattle Theatre to see In Transit.

In Transit, directed by Albert Maysles. Screening at the Brattle Theatre, Cambridge, MA, September 1 through 7.

A scene from “In Transit,” screening at the Brattle Theatre.

By Gerald Peary

Albert Maysles, who died in 2015 at age 88, was ubiquitous at universities and film festivals in his later years, never exhausted of tributes, of being at the center of attention. I did on-stage interviews with him twice, at Boston University and at the Provincetown Film Festival, and our conversations went the familiar way, with the black leather-jacketed filmmaker repeating as if spanking new the production stories of his long-ago documentaries, especially the world-renowned classics: Salesman (1969), Gimme Shelter (1970), and Gray Gardens (1975).

But was he still a relevant filmmaker, or just a nostalgic storyteller?

Maysles’s niece, Celia Maysles, basically accused him of being a fraud in her 2007 documentary, Wild Blue Yonder. She noted that Albert’s masterly films, such as the trio above, were all made in collaboration with his brother, David Maysles, Celia’s father. After David died in 1987, Celia claimed, Albert lost his capability as a filmmaker. For the next 20 years, he directed some minor projects but he was mostly a celebrity cameraman on other people’s films. That didn’t stop him from endless self-promotion, hogging credit for the important documentaries, barely acknowledging David’s genius.

Celia’s allegations were mean and perhaps exaggerated. But surely they were a kick in the tush for the prideful Albert Maysles who, in his final years on earth, awakened from his directorial sleep. In 2014, he made the well-received Iris, a series of camera meetings with the colorful nonagenarian interior designer, Iris Apfel. And he followed it with what would turn out to be his ultimate film, and among his best ever: In Transit Everyone who loves documentary, who cherishes the Maysles brothers’ legacy, should rush to the Brattle and see it.

In Transit was Albert Maysles’s dream project for many years, and with the simplest premise. He and a team of camera persons would spend days and nights on a long-distance train talking to the passengers and crew, and eavesdropping on conversations. What would they learn? The dream was realized with $600,000 funding from Al-Jazeera America. Maysles and four other filmmakers — Lynn True (also the editor), Nelson Walker, Ben Wu, David Unsui — climbed aboard Amtrak’s Empire Builder, a three-day ride from Chicago to Portland, Oregon, and Spokane and Seattle, Washington, with stops along the way in towns in Montana and North Dakota, and with a major changeover in passengers at Minneapolis-St. Paul.

And off they went!

For a time, In Transit seems pretty casual and uneventful, as the cameras jump from one passenger to another for brief introductory visits. The only real drama is with one young African-American woman headed to Minneapolis and deeply pregnant. Will her baby be born on the train before she makes it home? Yet as we the audience settle in for the long journey, as the hours seem to go by, the mostly normal-looking, slightly square-looking people start to open up to the cameras, to tell their life stories. Oh, the hidden heartbreak, the pain and anguish of so many!

There’s the old woman who, because of her cruel, abusive husband, gave away all seven of the children. There’s the young white woman who left home at 15, now is returning as a single mom with four biracial children, desperate that her family will accept her. There’s another young woman who admits, “I was born to a crack-head, raised by crack-heads and by military grandparents, and I should be dead by now.” There’s a group of drunken, uneducated men who are trying against reason to make their fortune in the crowded North Dakota oil fields, something out of The Grapes of Wrath.

Finally, there’s the aging ex-marine clutching a still camera. He’s suffering from depression, anxiety, a heart attack, “a repertoire of stuff.” He’s fled his family for this trip, “one more train ride,” needing to get away and obsessively photograph.

If this train is a microcosm of America, we see, so vividly, how class and race are determinates of success. The suffering above is that of the white underclass. Trump’s people, perhaps? The train also contains a cheery group of university students, who, unaware of all this misery around them, band together and party.

Even when these collegiates have problems, these are cushioned by their economic well-being. A white undergrad girl is lectured across the aisle by an ex-criminal black man, “You can be at the crossroads because you’ve got rich parents. I can’t be at the crossroads because I have to go to work.”

Again, this was Albert Maysles’s final film, his final testament, literally finished a few days before his death. He did not exit the earth leaving his audience in total gloom. The most moving scene in his film is one in which a kindly African-American deacon, a man who walked with Martin Luther King, comforts a very lost black man he has just met, helping him find a purpose, literally holding the man’s hand as the man cries like a newborn. “There is a spark of the human spirit that is not to be snuffed out,” declares the deacon.

And there’s the sweet-faced Midwestern boy who left his girlfriend when they were both 16 to head for the North Dakota oil fields. He’s now 24 and penniless but heading home to Indiana to see that same girl. Miraculously, she’s waiting for him.

The film ends with the advice of the young boy from his brother. Thus, the last words of Albert Maysles to all of us. And they’re sound ones.

“Go, be happy.”

Gerald Peary is a retired film studies professor at Suffolk University, Boston, curator of the Boston University Cinematheque, and the general editor of the “Conversations with Filmmakers” series from the University Press of Mississippi. A critic for the late Boston Phoenix, he is the author of nine books on cinema, writer-director of the documentaries For the Love of Movies: the Story of American Film Criticism and Archie’s Betty, and a featured actor in the 2013 independent narrative Computer Chess.