To watch a John Wick movie is to enter a criminal underworld with its own rules. A Wickiverse, if you will.

It is full of seemingly medieval rituals transferred to modern times. It began in its first chapter when a man sought vengeance upon those who killed his dog. Over the course of the first three movies, hundreds upon hundreds of humans died, too (302, to be precise). It probably won’t end until the franchise has used up every stunt person who ever dreamed of being on the big screen.

It continues the saga of a protagonist who is beaten up, stabbed, and bounced off moving cars. He survives falling a couple of stories or down a very long staircase. Yet he still jumps up and keeps fighting, as movie heroes must.

It takes place in locations like Paris, New York, Berlin, Osaka, and a nightclub where everyone keeps dancing while shooting and fighting is going on in their midst. It’s a landscape where a blind man can defeat a dozen heavily-armed men in a fight simultaneously. It’s a fantasy zone where Wick is handed a gun with a half-dozen clips that hold 21 shots each, yet he never runs out of ammo despite killing enough people to populate Portland, Maine.

The YouTube channel “By The Numbers” figured out that, over the course of the first three movies, Wick knocked off one person for every minute of screen time. That’s more dead people than in “All Quiet On The Western Front.”

When Sylvester Stallone starred in “Rambo: First Blood Part II” in 1985, he earned $12 million, making him the highest-paid movie star in the world. I timed all the dialogue he spoke in that film — a mere two minutes and ten seconds. In other words, he didn’t have to memorize a lot of lines. He was paid such a huge salary for the action sequences and his screen presence.

The same is true of Keanu Reeves, who might actually say fewer words as John Wick. But it’s his physical interaction with other characters — in gun battles, sword fights, and hand-to-hand martial arts combat — that makes this fourth installment as worth watching as the previous three. He’s ably assisted by a solid supporting cast. Ian McShane still manages to steal focus every time he opens his mouth. Donnie Yen plays the blind Caine as a man being forced to do exactly what he’s sworn he never would. Laurence Fishburne and the late Lance Reddick are as stalwart as ever. Clancy Brown makes the most of a representative of The High Table, the organization all of these folks work for in one way or another. And Bill Skarsgård gives an impressive performance as the smarmy Marquis, to whom they must answer.

There’s no sense in my explaining the plot of “John Wick: Chapter 4.” All you need to do is suspend your disbelief and give in to the protocols and conventions its characters adhere to, no matter how unlikely they seem. You have to accept that certain of them may seem dead, but aren’t. You have to accept that repeated scenes of ultra-violence can take place in the heart of many a major metropolis without anyone from law enforcement ever showing up. And most of all, you have to accept that the movie runs two hours and forty-nine minutes, so getting the two-gallon super-size soda at the concession stand may put your bladder to a big test.

“John Wick: Chapter 4” had a $90 million budget. Since, unlike in Alec Baldwin’s “Rust,” no real guns were used, that covers not only the cost of its lead actors, but also the enormous visual effects and stunt teams. I’m guessing that also includes the amount spent on candles, which may equal or exceed the number the numbers of bullets fired.

Reeves and his director, Chad Stahelski, have again delivered exactly what’s expected of them. If you see this fourth installment before the other three, you may miss out on some of the background lore, but if you’ve been along for the John Wick ride thus far, you’ll walk away satisfied. After you make a bathroom stop, of course.

If a “Jeopardy!” clue read, “The exact opposite of a movie based on a book by Jane Austen,” the correct response would be “John Wick: Chapter 4.” I’m giving it an 8 out of 10. Opens today in theaters.