Generally speaking, I am against the deaths of pets in movies; for my money, the thing that pushes Ridley Scott’s "Alien" over the line into absolute greatness is the survival of Jonesy the humorless cat. But there are exceptions to this rule, and one feels that Keanu Reeves’ widowed assassin, John Wick — whose adorable beagle puppy is killed near the beginning of 2014’s "John Wick" — has had the appropriate response to its death with a murderous rampage that, as of Friday, will have lasted for three fluorescent action movies.

Since this is a third serialized installment in what the studio clearly hopes will be even more movies, the film neither begins nor ends. It just sort of starts and, after a couple of hours stops, having expressed an encyclopedia of inventive martial arts scenes in the meantime. You can scoff at "John Wick: Chapter 3 — Parabellum’s" awful script, if you want to, and the lugubrious mid-film detour to Morocco (especially the Arabian prince getup they’ve foisted on poor Saïd Taghmaoui) really ought to embarrass everyone. But honestly, this third installment, like its predecessors, is only occasionally un-fun.

Keanu Reeves stars as 'John Wick' in JOHN WICK: CHAPTER 3 - PARABELLUM. Niko Tavernise

The high standards for the fight choreography and action scene design in "Parabellum," though, are inversely proportional to the quality of the dialogue, despite the several excellent performers present (Ian McShane, Anjelica Huston, Laurence Fishburne) to pretend their lines are speakable. For his part, Reeves’ own stoic, grief-stricken performance gives even the silliest moments some ballast; he is so often seen in gigantic spectacles that it’s easy to forget what a remarkable presence he is, holding his own next to master Shakespeareans and grizzled character actors.

Wick himself works as an assassin for The High Table, a Vatican-esque organized crime society that oversees the really classy murders through a chain of hotels where Table employees can get outfitted with contracts, guns and sorta-real bulletproof couture (a holdover from the second film that the third one never even bothers to mention) while saying ominous sounding fake-Latin phrases to each other. In the tradition of other gotta-top-the-last-one action movie series, from "James Bond" to "Mission: Impossible" to "Bourne," the aforementioned world-class actors swing by to gnaw on the scenery and expound on some of the series’ nonsensical lore.

Wick begins this particular emotional journey/ killing spree in medias res, having been declared “excommunicado” by The High Table for having had the temerity to kill someone at the end of the previous film on the grounds of one of The High Table’s hotels, The Continental, run by McShane’s Winston.

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Reeves himself is an oddly perfect counterpoint to the kitschy costumes, neon sets and pulsating music that enjoyably tease the older actors into hamming it up. He works not as a winking presence acknowledging all the absurdity, but as something like the opposite, wandering across the film wearing a funereal black suit and the wounded gaze of a man changed by suffering but untouched by irony or camp.

Extremely boring surprises follow, but the real twists in this film are in its fights, and those can’t be spoiled because they have to be seen to be believed. "Parabellum," like the rest of the "Wicks," is directed by Chad Stahelski, Reeves’s stunt double from "The Matrix," and his connoisseur’s eye for a well-fought brawl — with guns, knives, swords, fists or whatever happens to be at hand — is the engine that makes the movie run.

John Wick starts his rampage, for example, by dispatching a would-be murderer using a book from the shelves of the New York Public Library’s main branch, moves on to a delightful multifighter scene in what appears to be a closed museum dedicated to the preservation of elaborate knives, and passes through (as mentioned) Morocco, where he meets Sofia (Halle Berry) and her dual German shepherds, who leap into action, canis ex machina, every time their mistress is dealt a little more than she can handle.

There are Easter Eggs for fight nerds, too. Yayan Ruhian and Cecep Rahman, masters of Indonesian martial art silat, show up more or less as themselves at the end of the film for a pitched battle with Reeves — and, it absolutely must be said, his hard-working stunt double, Jackson Spidell.

Keanu Reeves and Halle Berry in JOHN WICK: CHAPTER 3 - PARABELLUM. Mark Rogers

The action scenes are propulsive but they’re also surprisingly varied: At one point, Wick’s enemies raid his allies’ base of operations and the sequence is staged like a horror film, with gruesome sound effects and villains leaping out of the dark as the camera’s eye passes them. The opening fight with the book could have come from a "Bourne" movie; the Morocco sequence looks like a homage to the "Indiana Jones" flicks; a gun battle lit with flashlights near the end of the film looks a great deal like a video game (a little unfortunately, it has to be said).

The story, though, lazily takes its cues from serialized television, with lots of portentous names for shiny accessories and hereditary titles that it doesn’t adequately explain, but as soon as it switches into action mode, it stops being TV and becomes a movie again.

For all that "Parabellum" barely pretends to have any connective tissue of a story between its fight scenes, there’s something undeniably moving about Reeves’ performance. He remains a magnetic actor and it’s hard not to recall his real-life personal tragedies — a stillborn child whose mother died 18 months later — as he seems to draw on some deep reservoir of pain in the midst of all the colored lights and posturing. It’s cotton candy grade violent entertainment for the unwashed masses, sure, but that doesn’t mean it isn’t at least a little bit true.

CORRECTION (May 21, 2019 11:01 a.m. ET): An earlier version of this article misstated the first name of Keanu Reeves' stunt double. He is Jackson Spidell, not Jason.