Proof is the story of an enigmatic young woman, Catherine, her manipulative sister, their brilliant father, and an unexpected suitor. They are all pieces of the puzzle in the search for the truth behind a mysterious mathematical proof. On the eve of her twenty-fifth birthday, Catherine, a young woman who has spent years caring for her brilliant but unstable father, Robert, must deal with the arrival of her estranged sister, Claire, and with the attentions of Hal, a former student of her father’s who hopes to find valuable work in the 103 notebooks that Robert left behind. What Hal discovers in an old notebook is a brilliant mathematical result that tests the sisters’ kinship as well as the romantic feelings growing between Catherine and Hal. 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? This poignant drama about love and reconciliation unfolds on the back porch of a house settled in Chicago’s Hyde Park.