Christian Wolff (Affleck) is a math savant with more affinity for numbers than people. Behind the cover of a small-town CPA office, he works as a freelance accountant for some of the worlds most dangerous criminal organizations. When the Treasury Departments Crime Enforcement Division, which is run by Ray King (J.K. Simmons), starts to close in, Christian takes on a legitimate client: a state-of-the-art robotics company, where an accounting clerk (Anna Kendrick) has discovered a discrepancy involving millions of dollars. But as Christian uncooks the books and gets closer to the truth, it is the body count that starts to rise.