Mona Gray was ten when her father contracted a mysterious illness and she became a quitter, abandoning each of her talents just as pleasure became intense. The only thing she can't stop doing is math - She knocks on wood, adds her steps, and multiplies people in the park against one another. When Mona begins teaching math to second-graders, she finds a ready audience. But the difficult and wonderful facts of life keep intruding. She finds herself drawn to the new science teacher, who has an unnerving way of seeing through her intricately built façade.