"John Wick: Chapter 3 — Parabellum" earned $57 million in its debut over the weekend, nearly doubling the opening of "Chapter 2."

The franchise started in 2014 with "John Wick," a low-budget action movie from first-time directors that received only one offer for distribution, from Lionsgate.

It's rare for sequels to consistently surpass their predecessors, let alone double their box office, but the "John Wick" franchise has settled on a winning formula, thanks to its action sequences and star, Keanu Reeves.

" While 'John Wick' seemed to come out of nowhere, you could also say there is a pent-up demand for these films, when cast appropriately," Jeff Bock, the Exhibitor Relations senior box-office analyst, said.

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A retired hit man whose wife recently passed away gets pulled back in when a group of thugs steals his car and kills his dog.

That's the premise of 2014's "John Wick," starring Keanu Reeves as the title character. On paper, it doesn't sound like the type of movie that would spawn two hit sequels, a fourth on the way, and an upcoming spin-off TV series, especially after considering its hard R rating.

But "John Wick," with its $20 million production budget, grossed four times that worldwide and kickstarted a successful franchise, the third movie of which — "John Wick: Chapter 3 — Parabellum" — just toppled "Avengers: Endgame" in its opening weekend at the domestic box office, ending "Endgame's" three-week reign at the top.

Read more: 'John Wick 3' dethrones 'Avengers: Endgame' at domestic box office after historic run

"They're doubling the opening weekends with each successive installment, which is rare indeed," Paul Dergarabedian, the Comscore senior media analyst, told Business Insider. "It's usually the opposite. It's the law of diminishing returns ... When there's a really well known IP they can start out bigger because there's excitement over something like that, but then it can diminish."

But "John Wick" made $14 million in its debut, "John Wick: Chapter 2" made $30 million in 2017, and "Chapter 3" earned $57 million.

So how does the franchise do it? To answer that question, it's important to understand the first movie's journey to the screen.

"John Wick." Lionsgate

An unusual action movie called for an unusual star

In 2014, Reeves hadn't led a box-office hit in over a decade. He had starred in several critical duds, such as "Constantine" and 2008's "The Day the Earth Stood Still" remake. Despite being a 1990s action star — with "Point Break," "Speed," and "The Matrix" — Reeves, then almost 50 years old, was an unlikely candidate.

But the script for "John Wick," originally called "Scorn" and written by screenwriter Derek Kolstad, starred an unlikely main character. Wick was a man in his early 70s, in the original script, who takes revenge against the men who killed the dog that was his wife's final gift to him before she died, according to Vulture.

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"He's no stranger to the mechanics of how a successful action film works," Jeff Bock, the Exhibitor Relations senior box-office analyst, said of Reeves. "And while he's also had just as many — if not more — bombs in his career, audiences are always willing to take another chance on him because of his past successes. And, well, there's no one quite like Keanu. People show up for action movies for action and distraction. That's where Keanu excels."

After Reeves boarded the movie, he brought on Chad Stahelski and David Leitch to direct. Both of them were stuntmen and fight coordinators on Reeves' "Matrix" movies but had never directed a feature film before. But they got the job (Leitch as an uncredited codirector) and fine-tuned some key parts of the story (according to Vulture, it was their idea to make Wick's 18-year-old dog a puppy).

Studios didn't seem all that interested in an R-rated action movie from first-time directors starring Reeves. But Lionsgate, which made the movie's only offer, eventually picked up the rights to distribute it, and audiences ate it up.

"The Wick franchise balances a sense of ridiculousness, fun characters, and a high concept story that have helped it succeed on so many levels," Shawn Robbins, the Boxoffice.com chief analyst, said. "The films never take themselves too seriously, but Reeves takes his character just seriously enough to keep them fresh and surprising."

Keanu Reeves and Halle Berry in "John Wick: Chapter 3." Lionsgate

'The planets aligned perfectly'

After the success of the first "John Wick," "Chapter 2" was an even bigger hit. Its budget doubled to $40 million, but it grossed $171 million worldwide. "Chapter 3" is already off to a strong start.

The closest franchise that Dergarabedian can compare "John Wick" to in terms of box office is "Austin Powers." When the first "Austin Powers" movie, "International Man of Mystery," was released in 1997, it made just $9.5 million (before inflation), but its 1999 sequel, "The Spy Who Shagged Me," debuted at nearly six times that at $55 million. The third movie, "Goldmember" in 2002, topped that, but not as impressively, with $73 million.

"The planets aligned perfectly for 'John Wick,'" Dergarabedian said.

Robbins compared the "John Wick" movies to the "Taken" series, which he said "came out of nowhere and gave Liam Neeson a new genre to thrive in for the past decade."

But not even Neeson's "Taken" trilogy, which also spawned an NBC TV series and is more in line tonally with "John Wick" than "Austin Powers," held strong over its three movies. "Taken 2" doubled the first movie's opening weekend with $49 million compared with $24 million. But "Taken 3" didn't reach its predecessor, debuting with $39 million.

The chart below compares all three franchises' opening weekends.

Bock said that "John Wick" filled a void in the action genre that audiences had been quietly craving.

"Action has taken a backseat to superheroes of late, so it's no surprise there are seats to fill in that genre," Bock said. "While 'John Wick' seemed to come out of nowhere, you could also say there is a pent-up demand for these films, when cast appropriately."

That demand seems to be during any time of the year. "John Wick" was released in October, "Chapter 2" in February, and "Chapter 3" in May. It makes the franchise's success even more impressive, but Lionsgate got the release date for "Chapter 3" especially right, according to Dergarabedian.

"It's the anti-summer movie," he said. "It's a very violent summer action movie. Usually those are released in August, when studios take risks on R-rated, hyper-violent films. But 'John Wick' provided a nice change of pace from the family films and superhero films that are out there. [Lionsgate] picked a good date, and the second weekend will be Memorial Day weekend, when movies get a good boost."

The "John Wick" franchise won't be slowing down anytime soon. A fourth movie is already set for release on May 21, 2021, and a spin-off TV series is in development at Starz called "The Continental," which is about the mysterious global hotel chain that functions as safe haven for assassins.

"Wick has tapped into this hunger for pure, star-driven, action entertainment for adults that never really goes out of style," Robbins said.

In other words, we're thinking he's back (and here to stay).