Why is Martin Scorsese back in gangster land? Surely “GoodFellas” and “Casino” nailed the subject.

But “The Irishman” is different. Yes, its cast and its post-World War II milieu constitute familiar Scorsese turf. But where “GoodFellas” made you understand how someone could be seduced by the Mafia world, “The Irishman” shows that world to be a cold one, without honor and humanity.

The film has gunplay, although the violence tends to be fast, clumsy and distinctly un-romanticized. This is an epic at ground level: conversations across humble restaurant tables, car rides to eerily vacant houses, the repeated image of two men softening their bread in red wine, a tradition so formal it’s practically a sacrament.

“The Irishman” is based on the much-disputed recollections of Frank Sheeran, a real-life mob guy whose ability to “paint houses” (that is, kill people) gave him steady work. He’s played by Robert De Niro, who — like the other actors — is digitally “de-aged” for the scenes that take place in his youth. (This looks weird at first, then you forget about it.)

Sheeran is employed by a Pennsylvania Mafia don, Russell Bufalino (Joe Pesci), who appreciates Sheeran’s simplicity. As the story — which includes dark hints about the Bay of Pigs invasion and the JFK assassination — winds from the post-WWII era into the 1970s, Sheeran becomes close to Teamsters president Jimmy Hoffa (Al Pacino).

Hoffa disappeared in 1975, a vanishing act that has never conclusively been solved. “The Irishman” gives Sheeran’s version of events, in a long, spellbinding sequence that takes up a big chunk of the film’s final hour.

If “The Irishman” has a weakness, it’s that this sequence provides a too-early climax. The slow wind-down by Scorsese and editor Thelma Schoonmaker is justified, but it’s still the only place you feel the 209-minute running time.

The period re-creation is meticulous, and Robbie Robertson’s original music compelling. With his customary use of songs, Scorsese does something amusing: The tunes on the soundtrack remain the kind of middle-of-the-road Italian-flavored instrumental hits these gangsters would’ve loved in the 1950s, even though popular culture changes through the years.

De Niro is strong, maintaining Sheeran’s bottled-up personality throughout. At one point Hoffa remarks on how hard it is to read Sheeran’s reactions; the line might apply to De Niro’s acting style, too.

Pacino is showier — yes, I know, surprise, surprise — but this suits Hoffa’s blustery style. I haven’t enjoyed a Pacino performance this much in years.

And yet Joe Pesci (mostly retired from acting for a decade) steals the movie, by underplaying. Pesci brilliantly gives you a guy so powerful he knows he never has to raise his voice.

The film is very good with unspoken things: The look in Pesci’s eyes after his mobster has just been insulted at a nightclub tells us that somebody is about to get whacked. Anna Paquin’s performance as Sheeran’s daughter is wordless, which fits. Too much blood has been spilled, and words can’t fix it.

Elsewhere, the dialogue in Steven Zaillian’s screenplay is excellent; when another mob boss (Harvey Keitel, nice cameo) warns Sheeran to spill the truth about something, he very precisely says, “Now is not the time to not say.”

Other actors fly past as the years go on; Ray Romano is wonderful as a mob lawyer, and Sebastian Maniscalo makes an impression as the ill-fated Joey Gallo.

This is a completely lived-in film by a master craftsman. Everything from the color of the drapes to the way people eat cereal has been shaped; you can feel Scorsese’s care.

All of this is paid for by Netflix, probably the only entity with deep enough pockets to bankroll $160 million for a tale that ends with a profoundly chilling sense of emptiness. Their money bought them a classic.

“The Irishman” (4 stars)

A meticulously made gangland classic from Martin Scorsese, with the powerhouse cast (sometimes digitally de-aged) of Robert De Niro, Al Pacino and Joe Pesci. It’s an un-romanticized view of mob life, a 209-minute intimate epic that leads to a profoundly chilling conclusion — and it’s Scorsese at the height of his powers.

Rating: R, for violence

Opening Friday: Cinerama, Crest; streaming on Netflix beginning Nov. 27