This had a promising premise but was bogged down by flashbacks, a long explanatory sequence (that included more flashbacks), and reveals that weren't all that surprising (except one at the very end that was pretty cool).
Ben Affleck, in an attempt to prove to Matt Damon that he can also play "smaht," is a math savant on the autism spectrum that works as—wait for it—an accountant. But also works for bad people, I guess? Because J.K. Simmons is there as a Treasury Department officer trying to track this accountant down.
Affleck—whose character is named Christian Wolff—takes a job for a company called Living Robotics, run by John Lithgow. There are some, let's say, discrepancies in the books, and then this other team of guys is going around killing people off to keep the truth from coming out. Chris and a Living Robotics accountant named Dana (Anna Kendrick) are on the hit list. Lucky for Chris, and actually also for Dana, that there are a lot of flashbacks to tell us how Chris' military father had him and his brother trained to fight and kill.
Honestly, the whole thing is a kind of mishmash mess with almost too much going on and lots of things filmed in heavy shadow. And then it grinds to a complete halt when J.K. Simmons goes into a long voiceover that explains Chris' criminal background and how he (Simmons) got pulled into the mystery of who this guy is. By that time, I'd all but lost interest. Still, I'm glad I finished it out if only for the final little reveal at the very end of the film. There's at least one other reveal before that, but it is underwhelming and not at all surprising.
I'd really had hopes for this movie. It had such potential. But oh, it really needed to be edited and tightened. As it stands, it's somewhat sloppy and periodically flat-out boring.