It focuses on Catherine, a young woman who has spent years caring for her father, Robert, a brilliant mathematician in his youth who was later unable to function without her help. His death has brought into her midst both her sister, Claire, who wants to take Catherine back to New York with her, and Hal, a former student of Catherine's father who hopes to find some hint of Robert's genius among his incoherent scribblings. The passion that Hal feels for math both moves and angers Catherine, who, in her exhaustion, is torn between missing her father and resenting the great sacrifices she made for him. For Catherine has inherited at least a part of her father's brilliance -- and perhaps some of his instability as well. As she and Hal become attracted to each other, they push at the edges of each other's knowledge, considering not only the unpredictability of genius but also the human instinct toward love and trust.