Catherine has sacrificed her education and social life to care for her brilliant but unstable father during the worst of his mental degeneration.

On the eve of her twenty-fifth birthday Catherine must deal not only with the arrival of her estranged sister, Claire, but also witht he attentions of Hal, a former student of her father’s, who hopes to find lingering insight in the professor’s work.

As Catherine confronts Hal’s affections and Claire’s plans for her life, she struggles to solve the most perplexing problem of all: How much of her father’s madness or genius will she inherit?

David Auburn’s compelling script ricochets between the mysteries of mathematics, the elusiveness of love and the fine line between genius and madness.