Dir: Gavin O’Connor. US. 2016. 128mins

The Accountant doesn’t add up, but this Ben Affleck vehicle can be awfully entertaining despite (or perhaps because of) its general ludicrousness. An action-thriller about an autistic forensic accountant who also just so happens to be a lethal assassin, the latest from director Gavin O’Connor (Warrior) is part character study and part airport-novel nonsense, and the film’s utter chutzpah gives the proceedings an agreeable kick. But The Accountant can’t balance its B-movie instincts with its more artistic aspirations, ultimately hamstringing a potentially juicy, escapist shoot-‘em-up.

The Accountant dares you to take its cockeyed story seriously, which becomes a problem when the film actually tries to get serious

Hitting US theatres October 14, this Warner Bros release will be competing with similar fare in Jack Reacher: Never Go Back and Inferno, the studio no doubt hoping that Affleck’s star power can stand up to that of Tom Cruise and Tom Hanks. Solid grosses seem assured, but don’t expect The Accountant to tally record-breaking numbers.

Affleck plays Christian Wolff, a mild-mannered, heavily-in-demand corporate accountant who is also a high-functioning autistic - meaning he struggles to engage in basic social pleasantries. This maths genius is hired to look into financial irregularities in a robotics company, where he meets Dana (Anna Kendrick), an accounting clerk who first noticed the discrepancies. Soon, though, he becomes the target of a contract killer (Jon Bernthal) at the same time as being tracked by a Treasury Department agent (J.K. Simmons) who believes he is an elite hitman.

Those seemingly incongruous descriptions of Wolff — accountant and assassin — are the key to The Accountant’s loopy energy. For much of the film’s first half, we learn how Wolff struggles with his autism, requiring medication and resigned to a life governed by structure and repetition. Affleck strips away his usual charisma and puppy-dog earnestness to play Wolff as a stoic, closed-off man who lives in his head, unable to reciprocate Dana’s kindness.

It’s a competent performance that, nonetheless, feels more than a little mannered — an impression that grows stronger once we realise that Wolff is also an expert marksman and a stunningly proficient killer. Ironically, The Accountant allows Affleck to play two types of roles that made his friend Matt Damon famous: that of the misunderstood maths prodigy (from Good Will Hunting) and the unstoppable, ass-kicking warrior (from the Jason Bourne films). Affleck’s character may apper to be devoid of personality, but the actor still manages to make Wolff’s placid expressions sympathetic — or even comic, when the situation requires.

But although O’Connor directs with his usual stripped-down efficiency, The Accountant can’t justify the leaps of logic that Bill Dubuque’s screenplay requires of the audience. Through flashbacks, the film demonstrates how Wolff acquired his combat skills from a gruff Army father who didn’t want his boy being tormented by bullies. O’Connor presents this information with the tortured gravitas of a comic book hero’s dark origin story — in a way, Affleck is again playing a Bruce Wayne figure after Batman V Superman — but it comes across as overwrought. And without ruining any plot twists, let’s simply say this is but the first of several audacious hairpin turns The Accountant takes, but O’Connor never quite sells.

To be fair, there can be considerable pleasure in the film’s unabashed implausibility, with O’Connor brazenly amplifying the storyline’s movie-ish artificiality. And once The Accountant reveals Wolff’s true nature, the director crafts some taut action sequences. The film’s tonal shift from sombre drama to down-and-dirty thriller gives The Accountant a pleasant jolt as we’re suddenly presented with a protagonist who’s very different than the man we thought we knew.

Unfortunately, O’Connor also mixes in a half-hearted love story between Wolff and Dana — Kendrick radiates sweetness but doesn’t have enough to do — while also dropping surprises that are clever but also terribly convenient. In addition, The Accountant tries to do something mildly provocative by making its main character autistic, arguing that people with the condition are just as capable of being inventive, powerful heroes. That’s a laudable, inclusive notion, but the movie’s simplistic, quirky treatment of autism falls far short of being noble or instructive. The Accountant dares you to take its cockeyed story seriously, which becomes a problem when the film actually tries to get serious.

Production companies: Electric City Entertainment, Zero Gravity Management, RatPac-Dune Entertainment

Worldwide distribution: Warner Bros., www.warnerbros.com

Producers: Mark Williams, Lynette Howell Taylor

Executive producer: Gavin O’Connor, Jamie Patricof, Marty P. Ewing, Steven Mnuchin

Screenplay: Bill Dubuque

Cinematography: Seamus McGarvey

Production design: Keith Cunningham

Editor: Richard Pearson

Music: Mark Isham

Website: www.accountantmovie.com

Main Cast: Ben Affleck, Anna Kendrick, J.K. Simmons, Jon Bernthal, Jeffrey Tambor, John Lithgow