If Jimmy Hoffa were aware that his mysterious 1975 disappearance would lead to his being played onscreen by both Jack Nicholson and Al Pacino—and that in the latter case the film would be directed by Martin Scorsese—he might, always having been a larger-than-life publicity hound, appreciate getting attention from the very best.

He might not, however, enjoy playing second fiddle to somebody not nearly as well known—Frank Sheeran, the titular character of Scorsese’s “The Irishman,” played by Robert De Niro. Sheeran was a truck driver who became part of the crime family of Pennsylvania mafia boss Russell Bufalino (Joe Pesci) and, on Bufalino’s recommendation, was hired by Hoffa as an aide-de-camp. When Hoffa ultimately fell into disfavor with the mob, Sheeran confessed when approaching his own date with the grim reaper, he killed Hoffa on orders from Bufalino.

Case solved? Hardly. Sheeran’s claim, reported in Charles Brandt’s book “I Heard You Paint Houses,” has never been independently verified and has been widely derided as just the most outrageous lie of a man who constantly embellished his career, and what happened to Hoffa remains a matter of intense dispute. But his story is the one told by Scorsese and screenwriter Steven Zaillian in their film. So does it matter that from a historical perspective the film, while it contains a great deal of plausible period context, might be hooey in terms of its most fundamental contention?

Only if—as some people did with a movie like “JFK”—you take the film as a docu-drama. It’s not, of course. “The Irishman” should be seen as the culmination of the series of mob-centered films Scorsese, De Niro and Pesci have made together over the years—a long but richly textured, melancholy elegy about a way of life ostensibly based on comradeship but really founded on selfishness and violence. Taken together, “Goodfellas,” “Casino” and “The Irishman” are as masterful a trilogy about the Mafia as the “Godfather” series. And on its own “The Irishman” is a remarkable capstone to Scorsese’s work in the genre.

At three-and-a-half hours it’s an epic in terms of length, but an intimate one that follows Sheeran as he’s accidentally drawn into the mob and then carried along by its pull to the end of his life. (One much-discussed element of the picture is its employment of a computer-based de-aging process on the actors, particularly De Niro and Pesci. It’s still not flawless, but in contrast to the recent “Gemini Man,” works remarkably well here—mostly very convincing, and rarely distracting. As with the 3D of “Hugo,” Scorsese demonstrates how technology can be employed to enhance rather than intrude.)

Frank is no saint to begin with: a World War II veteran turned deliveryman, he shows his brutal side when he beats up a store owner he believes as mistreated his young daughter Peggy (Lucy Gallina), who’s taken aback by her father’s volatile temper. It’s not until Bufalino gives him an assist after his truck has stalled, and later takes him under his wing, however, that his propensities really come to the fore. Throughout their relationship, he will submit his inclinations to Bufalino’s directives (a sequence in which he’s enlisted to bomb a laundry business by an outsider without checking with the boss first proves that), and Peggy is instinctively repelled by the childless Russell’s attempts to ingratiate himself with her, further poisoning her relationship with her father, which, as the wraparound frame of the film—in which the aged Sheeran, ensconced in a nursing home, looks back on his life—is never healed.

Under Bufalino’s protection, Sheeran advances in the organization; almost without choosing it, he becomes a handy enforcer and hit-man. And when Hoffa, who’s been investing his Teamsters Union funds in mob businesses for years, finds his leadership threatened by rivals—and by government investigations that he sees as betrayal, coming from the Kennedys who won office in part with Mafia support—Bufalino recommends Frank to him for his skills at both intimidation and personal protection. Gradually the two men become friends, and Sheeran is in the position of trying to protect Hoffa—whom Peggy has, incidentally, taken a shine to—from himself as well as his enemies, including his union rival Tony Provenzano (Stephen Graham); he, like Hoffa, is sent to prison in the late sixties, leaving Hoffa’s hand-picked stooge Frank Fitzsimmons (Gary Basaraba) as union president.

After both men are released, however, their feud continues as Hoffa tries to regain control of the union from Fitzsimmons. Frank tries to mediate between them, but his efforts to calm Hoffa fail to bear fruit; at the same time he’s called on to settle mob business of a bloodier sort, like dealing with out-of-control Brooklyn gangster “Crazy Joe” Gallo (Sebastian Maniscalco), whom he claims to have assassinated at Bufalino’s direction.

Matters with Hoffa come to a head in 1975, when he threatens to reveal secrets of both union officials and Mafia chieftain to authorities. During a car trip to Ohio for a wedding with their wives (Stephanie Kurtzuba and Kathrine Narducci), Russell informs Frank that a decision has been reached to kill Hoffa, and that he is to be the gunman. Sheeran’s account of the killing is followed by a postscript showing him and Bufalino in prison convicted of other crimes, and Frank in the nursing home after his release, meeting with Brandt but rejected by his family, especially Peggy (Anna Paquin), who suspects his involvement in Hoffa’s disappearance.

“The Irishman” features some nice supporting turns–by Paquin, Graham, Maniscalco, Bobby Cannavale as another of Bufalino’s underlings, Ray Romano as his shady lawyer and—in what amount to a cameo—Harvey Keitel as Angelo Bruno, a colleague of Bufalino in the mob leadership. But the film relies on its three stars, and all are superb. Pacino is expectedly volcanic as Hoffa, capturing both his charisma and his sudden fury. De Niro offers a rich and nuanced turn as a man who must suppress his natural intensity to cater to Hoffa’s demands and even grovel before Bufalino’s.

The real revelation, however, is Pesci, so often pegged as over-the-top, who gives a remarkably restrained performance as the influential “quiet don,” yet adds an unmistakable measure of menace to Bufalino as well: his stillness is more frightening than the rants of Gallo or Hoffa. It’s a great performance.

Of course the ultimate star is Scorsese, who brings all the mastery he’s developed over decades to bring Frank Sheeran’s story, however truthful it might be, to life. True, one occasionally might feel that the film could have benefited from some additional trimming by editor Thelma Schoonmaker, but to reverse Pauline Kael’s famous observation after seeing the original “Heaven’s Gate”—that she could think of much to cut but nothing to keep—in this case one might talk in the abstract of shortening the film, but it’s difficult to think of specific parts you’d remove. The other craft contributions are all excellent, from Bob Shaw’s production design and the costumes by Christopher Peterson and Sandy Powell to Rodrigo Prieto’s smooth cinematography. And as noted the visual effects supervised by Pablo Helman are superb.

The only real complaint one can lodge against “The Irishman” is that as a Netflix project, it will be shown in a very limited number of theatres for only a short time before migrating to the streaming service. The running-time will not seem excessive there, of course, but Scorsese’s film deserves to be seen on the big screen. Still, one has to thank Netflix for putting up the substantial production cost when the Hollywood studios balked, preferring instead to try to find their next tent-pole franchise, presumably involving some superhero or other. It’s sad that their slates can no longer accommodate a film like this—a powerful, thought-provoking, brilliantly crafted work of art by an unquestioned master of the medium.