Proof

"One of the most acclaimed plays of recent seasons, Proof explores the unknowability of love as much as it does the mysteries of mathematics.".

"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 not only with his death but 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.".

"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?"--BOOK JACKET.

Synopsis from Open Library.