The American cinema of the ’70s is justly celebrated for daring and intellectually challenging film, cynical cinema that pointed the camera at urban and rural decay.

The skepticism of the “Hud” and “Midnight Cowboy” 1960s curdled into grim portraits of a nation in decline just past the cusp of its greatest triumphs.

John Huston’s film of Leonard Gardner’s 1969 novel “Fat City” is a classic of this seedy cinema of the underclasses, a compelling drama of “the fight game” that grappled with bitterness and a generation facing the disappointment of the dashed American Dream.

It’s a boxing picture that isn’t about the boxing, save as a metaphor for the violence of lives at the bottom with little prayer of escaping their fate. Hardboiled and booze-fueled, it was a career-maker for Stacy Keach, an Oscar-nominated revel for Susan Tyrell and a great stepping stone for Lloyd Bridges’ younger son, Jeff Bridges, long and lean and hungry in his “Last Picture Show” years, here playing a lanky kid proclaimed as a “natural” by people we realize are grasping at the same straws that he is and kidding themselves as they do.

We meet Tully (Keach) as he staggers out of bed, takes a sip from a bottle in the Stockdale, California flophouse hotel room’s nightstand, and saunters into the street. Maybe today’s the day he’ll get back in shape. So he visits the nearly empty YMCA. That’s where he meets “the kid” mastering the punching bag.

Ernie Munger (Bridges) is muscular but lean. He agrees to “spar a little” with grizzled Tully, a fighter he recognizes but who hasn’t fought for a year and a half.

“I think you got it, kid.”

That’s enough to send 18 year-old/no-prospects Ernie to meet with Tully’s old trainer, Ruben (Nicholas Colasanto, a decade before “Cheers”). Ruben repeats Tully’s compliments. They’re all impressed by the length of the kid’s arms, his “reach,” and figure Ernie could “make a lotta money, if he’s handled right.”

Keach’s Tully is the focus in a narrative that introduces our two protagonists to each other and separates them for much of the picture before a bitter-with-barely-a-hint-of-sweet reunion. Huston, who took boxing seriously for a stretch of his youth, knew this world and brings a romantic fatalism and grit to his only film set in that milieu.

Tully cadges drinks and closes the bars down, talking with the deluded chatterbox Oma (Tyrell) and her man Earl (Curtis Cokes). There’s a tolerance and affection between them that suggests maybe our hooker/pimp guess about their relationship is wrong. When Earl goes to jail, Tully takes up with her, another obstacle to him ever putting the gloves on again. Then again, maybe he’ll swallow his pride and bitterness and reunite with Ruben.

Ernie’s got a girlfriend (Candy Clark) who clings to her first lover, not because she thinks he’s her ticket out, but because that’s the only life she can see ahead of her. Ernie’s earliest bouts don’t have him convinced that boxing is their salvation, but with a baby on the way, he marries her and their fates are sealed.

Huston had three guideposts to lead himself and the viewer through this world — Gardner’s script adapted from his own novel, the generational farm working poverty of agricultural day labor of Stockdale, and Kris Krisofferson’s soulful version of his recent pop and country hit, “Help Me Make It Through the Night.” That anchors movie’s score and wafts through scene after scene of barflies drinking, the barely-hidden despair of teen lovers living at the dead end of America, or of the drunken Tully facing another “Sunday Morning Coming Down.”

The boxing scenes are modestly realistic without the far-fetched melodrama of decades of “big fight” movies. They’re here to say something about the characters and what they’ll put themselves through because they just don’t know any better.

Huston is just as interested in the hard, sweaty labor of chopping onions or picking vegatables in the fields around Stockton, an impoverished workforce of Blacks, Latino migrants or others who have run out of options and face the cruel exploitation of this work out of desperation.

“How long before a man gets used to this, anyway?”

“I’ve been doin’ it for twenty-five years and ain’t got used to it yet.”

Huston was from a different era, and the film’s racial attitudes not only reflect that, they comment on it. Tully is a “young white man” whom others figure should have other choices in work and career. He and Ernie are white boxers, and “white guys don’t wanna buy tickets to go see two colored guys fight.”

Wayne Mahan plays the cocky young fighter Buford, whose idol has to be Muhammed Ali. But they’re all equals in the ring, and a loser is a loser — excuses or dirty tricks notwithstanding.

Earl is depicted as a victim of his circumstances but a strict adherent to the Guy Code. “All a man needs is a woman with a good job.” Even if the woman kicks you out, you don’t throw out her ex-lover’s stuff. You hold it for him.

Ex-boxer Sixto Rodriguez quiently ennobles his character, a has-been recruited against doctor’s orders to co-headline with has-been Tully.

Huston’s storied career makes the subject of “his best decade” a favorite topic of debate among critics. His 1940s classics helped define film noir and earned his actor daddy Walter an Oscar for “The Treasure of the Sierra Madre.” He put “The African Queen,” “The Asphalt Jungle,” “The Red Badge of Courage” and “Moby Dick” on the screen in the ’50s. His ’60s cinema included some of his most serious work — “Reflections in a Golden Eye” and “The Night of the Iguana.”

And just when everybody wrote him off for making pop kitsch like “Victory” and “Annie,” he made an end-of-career comeback with “Under the Volcano,” “Prizzi’s Honor” and “The Dead” in the ’80s.

But the ’70s were when he finally got his long-dreamed-of Kipling adaptation, “The Man Who Would be King,” on the screen. He had his best roles as an actor in “Chinatown” and “Winter Kills.” He adapted Flannery O’Connor’s “Wise Blood” and made one of the great if quixotic fin de siecle Westerns, “The Life and Times of Judge Roy Bean.”

And he made his boxing picture, the ironically titled “Fat City,” one of the most vivid snapshots of a grey and greying era filmed as it was happening and a bellwether film in the careers of two terrific actors whose careers diverged in most ways save for one — the critical acclaim that has come to them much later in life.

Rating: PG, boxing violence, alcoholism, smoking

Cast: Stacy Keach, Jeff Bridges, Susan Tyrell, Candy Clark, Curtis Cokes, Art Aragon, Sixto Rodriguez and Nicholas Colasanto.

Credits: Directed by John Huston, scripted by Leonard Gardner, based on his novel. Columbia Pictures release on Youtube, Hulu, Amazon, other streamers

Running time: 1:36