Jon Bernthal and Ben Affleck return in “The Accountant 2.” (photo courtesy of Amazon MGM Studios)

After nine years, Ben Affleck returns as the numbers guy with a mission and an assault rifle. Nobody asked for this, but here we are with “The Accountant 2.” At least Jon Bernthal is a delight.

The particulars of the story are, well, convoluted. A former government official dies, but he leaves behind a message: “Find the accountant.” Federal agent Medina (Cynthia Addai-Robinson) knows who that is.

By day, Christian Wolff (Ben Affleck) is a forensic accountant for unsavory figures, sometimes solving a dating organization’s algorithm in a side quest that ends where it began. By night, he counts his righteous kills. Why does he do any of this? The first film never quite clarifies that, and the sequel seems to defer to the first one.

Medina begrudgingly seeks him out to uncover a mysterious missing persons case that involves human trafficking, gangs and plenty of shady foes, including assassins like Cobb (Grant Harvey) and Anais (Daniella Pineda), whose allegiances are unclear.

Eventually, Chris brings his assassin brother, Braxton (Bernthal), into the mix, which only exacerbates Medina more. Working outside the law is difficult enough. Add siblings raised to be killers, and the outcome will turn violent soon enough. But before these brothers unite in combat, they talk … a lot.

For an action film, very few fight sequences occur. This is especially odd considering the film’s $80 million budget (double the first film). Some modest sequences peppered the film. A bathroom fight here, a house fight there. But more impatient viewers won’t be satisfied for about 90 minutes until things pick up. Perhaps the goal was to save it all for a grand finale.

“The Accountant” relied on a central mystery only Chris could solve. Braxton seemed like the big bad until the climactic reveal. This time around, the storyline is an excuse for the pair to share the screen together. Bernthal features his usual swagger and drawl, while Affleck returns to a more subtle role as this high-functioning autistic character.

Remember 2018’s “The Predator,” including a subplot about autism and human evolution? Place that one in the backhanded compliment category. “The Accountant 2” isn’t necessarily an insulting or patronizing depiction of autism, but it’s hardly a major win for neurodiversity on the big screen. Chris’ team of hackers (that convenient plot device is a whole other thing) often makes socialization recommendations, while Braxton and occasionally Medina help out with social norms as well. Such exchanges appear innocent and helpful enough, but so much of the film features people establishing Chris as an outsider, none trying to learn more about his point of view.

And for a second time, the films series is allergic to the word “autism,” favoring the more ambiguous “condition” or Chris once referring to those hackers as “my people,” implying much. Why term aversion, who knows?

That MGM greenlit this sequel is an odd choice for a couple other reasons. First, its predecessor did OK at the box office, but nearly a decade passed without much public interest in a sequel. Second, split critics down the middle on that one’s quality. The first one is better, though both films enjoy similar problems, like pacing and how to reveal certain mysteries along the way.

“The Accountant 2” is a fine film with two actors who clearly enjoy what they’re doing on screen. Affleck and Bernthal’s commitment to these films shows. If only writer-director Gavin O’Connor (“Miracle,” “Warrior”) could figure how to make the formula pop by the third film, which is already in development. What’s here is comparable to many Netflix and Prime actioners, but hardly an epic experience that’ll help theaters heal.

“The Accountant 2” has action, as well as some issues with pacing. (photo courtesy of Amazon MGM Studios)