“Logan”

***

(R, 2:15)

In “Logan,” the clawed mutant Wolverine finally gets to slash through the constraints of a kid-friendly PG-13 rating, and the result is bloody, vicious fun. The squeamish will avert their eyes, and young children should not be allowed anywhere near this movie, no matter how many X-Men action figures they own.

But fans of the beloved Marvel Comics character — arguably the most lethal in all of comic-book land — will relish the sight of the hot-tempered hero in his full limb-and-artery-slashing glory. The violence in “Logan” isn’t played for kicks, like it was in “Deadpool.” It’s grave and serious and sometimes hard to watch, which fits in with the overall tone of this grim, surprisingly downbeat movie.

Director James Mangold, who began digging into this character’s dramatic potential in 2013’s “The Wolverine,” has made a comic-book movie that feels like it takes place in the real world. The film checks off all the elements the genre requires: big action set pieces, chases, super-villains and fan shoutouts (an old “X-Men” comic book plays an important role in the plot).

But Mangold resists the temptation to overstylize and exaggerate, the way most movies of this kind do. And he doesn’t gloss over the consequences of violence, either: One sequence, in which the heroes camp out at a remote house intending to get a good night’s sleep, takes such a dark and calamitous turn it briefly turns “Logan” into a hair-raising horror movie — the kind that leaves a bruise.

“Logan” challenges an audience coddled by CGI spectacle right from its stark, plain opening credits. Wolverine (Hugh Jackman) is a functioning alcoholic working as a limo driver in a border town. He lives in seclusion with Caliban (Stephen Merchant), an albino mutant who fries in direct sunlight like a vampire. He looks after Professor Xavier (Patrick Stewart), now in his 90s and feeble (the movie takes place in 2026) and suffering from seizures that paralyze anyone who happens to be standing near him.

Wolverine isn’t doing that well himself: His regenerative powers, which allow his wounds to instantly heal, have slowed, and the adamantium steel that forms his skeleton and claws has become toxic. A Mexican immigrant (Elizabeth Rodriguez) holed up in a dingy motel offers him $50,000 to take Laura (Dafne Keen), a curious 11-year-old who doesn’t say much, to a safe haven near the Canadian border. But Logan refuses: His days of heroic do-gooding are over. All he wants to do is save up enough money to buy a nice boat and spend the rest of his life sailing around the world.

Then some mean-looking dudes in a caravan of black SUVs come looking for the girl, and what has been a dour, off-putting, vaguely depressing movie suddenly roars to rousing, savage life. The script for “Logan,” which was co-written by Scott Frank (“Out of Sight,” “Minority Report”), doesn’t follow the typical comic-book formula. There are no bad guys intent on destroying the world, no giant beams of blue light that must be stopped before it’s too late. The stakes are low but critical, and the father-daughter relationship that develops between Logan and the girl is sweet and sincere (the fact that she’s just as ferocious a fighter as he is helps them bond quickly).

“Logan” loses a bit of momentum in its final half-hour: The requisite lull before the big action finish goes on a little too long, and the movie could have shaved 10 minutes from its two-and-a-quarter hours. But this is Jackman’s signature role, the one that will forever define his career, and after playing the character in six movies (and two cameo appearances), you can’t begrudge the guy a protracted farewell. This is a sadder, wearier Wolverine than the one familiar from the comics, but the actor has made the role his own. After all its bloodshed and mayhem, “Logan” ends on a graceful, melancholy note, proving that sometimes, comic-book movies work best when they keep things small.