Ben Affleck stars as the titular accountant, a highly functional autistic savant and skilled fighter/gunman named Christopher Wolff, who currently has an office at a strip mall that fronts for his real business, and a lucrative one at that, as the under-the-radar forensic accounting wunderkind who helps save major businesses, governments, and underworld figures willing to pay an exorbitant price. His latest client is a famed roboticist named Lamar Black, who wants the accounting dynamo to go through his books to find out why his own accountant, Dana Cummings, is having trouble with some of the numbers that aren't adding up, potentially resulting in a major financial leak in profits. When his work is cut short, Wolff can't bear to stop without achieving completion, though the Treasury agents on his tail threatens to undo everything he's built up before that can happen.