Ben Affleck and Anna Kendrick in a scene from “The Accountant.” (Chuck Zlotnick/Warner Bros. Pictures via Associated Press)

This post discusses the plot of “The Accountant,” but not really the elements that are important to the thriller-y bits.

This has been a moviegoing season full of surprises — really, a year full of surprises, many of them unpleasant — so who am I to protest that “The Accountant,” a movie that’s been sold as a sinister thriller, is actually at times a funny, sweet movie about people on the autism spectrum?

The film, which has been sold as a rather dour slog, is something else entirely. Ben Affleck plays Christian Wolff — or at least, that’s the name his character is going by at this particular moment. Christian was raised by his father (Robert C. Treveiler), an Army man who equates shows of strength with normality, after his mother, who wanted to pursue a kinder course of treatment for Christian’s autism spectrum disorder, left the family. Christian grew up to be the sort of person who launders money for criminal syndicates while using small-town accounting businesses as a front, taking payment in fine art and keeping an Air Stream full of guns, gold bars and new identities.

There’s a lot of rigmarole in “The Accountant” that could have been cut out; a 90-minute version of it might have had a shot at action-comedy classic status. But rather than dwell on these problems, which aren’t mine to fix, I’d rather discuss what makes “The Accountant” so surprising.

“The Accountant” is not an argument — as I know some parents of kids on the spectrum had worried — that having an autism spectrum disorder makes you an obsessively good financial analyst by day and Batman by night. It’s an argument that having an autism spectrum disorder could make you an obsessively good financial analyst, and that if you have a crazed, abusive father in military intelligence with the resources to hire an international bevy of martial arts masters to train you, you might also become Batman.

Conceit aside, someone involved in the making of “The Accountant” clearly knows something about the autism spectrum. The movie does a nice job of explaining things like sensitivity to certain fabrics, light and sound, and behaviors like stimming, or self-stimulation. “The Accountant” recognizes that the autism spectrum is, in fact, a spectrum, and that it can manifest in different ways, rather than simply turning out taciturn super-geniuses. It would have been nice if one particular character on the spectrum, played by the marvelous Alison Wright, had a bit more screen time, but as standards-setting goes, “The Accountant” is a reasonable start.

Among the highest virtues of “The Accountant” and its treatment of autism spectrum disorders is that it acknowledges the challenges Christian has faced — as much from his father as from his diagnosis — without rendering him a merely tragic figure. Among other things, Bill Dubuque’s script does a deft job of striking a balance between allowing Christian to be unintentionally funny without making him the butt of a joke.

In one scene, he explains to Dana that he likes paintings of dogs playing poker, “Because dogs would never bet on things. It’s incongruous.” On one level, Christian is missing the obvious point, that animals don’t play cards. But on another, he’s completely right, and this throwaway line casts an iconic piece of American kitsch in a new light.

In another scene, Christian dispatches a threat to Frank and Dolores Rice (Ron Prather and Susan Williams), a nice Midwestern couple whom he helped with taxes, with efficient and highly lethal force. Once he’s done, he gives them an awkward wave, which makes the point: Really, what do you say after effectively revealing yourself to be a superhero?

Another smart element of the movie is the flirtation between Christian and Dana (Anna Kendrick), a young accountant who discovers a discrepancy in a robotics company’s books that leads executives to hire Christian to do a forensic audit.

As much as I’m irritated that Hollywood can’t find better things to do with Kendrick, she’s the rare actress who could light up while discussing the emotional pleasures of setting a ledger to rights — she can light up while doing anything. Watching them find common ground in math and odds is a testament to the idea that the difference between Christian’s interests and abilities and Dana’s is one of degrees. The bond they form puts some heft behind a line at the end of the movie, when we see a neurologist (Jason Davis) tell a couple that they shouldn’t rule out the possibility that their son will have relationships and even get married.

In its own, off-kilter way, “The Accountant” is a genuinely hopeful movie.