Germaine Johnson doesn’t need friends. She has her work and her Sudoku puzzles. Until, that is, an incident at her insurance company leaves her jobless—and it turns out that there are very few openings these days for senior mathematicians with zero people skills.

Desperate, Germaine manages to secure a position at City Hall answering calls on the Senior Citizens Helpline. But it turns out that the mayor has something else in mind for Germaine: a secret project involving the troublemakers at the senior citizens center and their feud with the neighboring golf club—which happens to be run by the dashing yet disgraced national Sudoku champion, Don Thomas.

Don and the mayor want the senior center closed down and at first, Germaine is dedicated to helping them out—it makes sense mathematically, after all. But when Germaine actually gets to know the group of elderly rebels at the senior center, they open her eyes to a life outside of boxes and numbers and for the first time ever, Germaine realizes she may have miscalculated.