In the Pulitzer and Tony-winning drama Proof, David Auburn has fashioned an extraordinary play – a gripping exploration of loss, guilt, discovery, love and the elusive nature of truth. Catherine has spent years caring for her brilliant but unstable father, Robert. When he dies she has more than grief to deal with: There’s her estranged sister, Claire, and Hal, a former student of her father’s who hopes to find valuable work in the 103 notebooks that Robert left behind. And a further problem: How much of her father’s madness – or genius – will Catherine inherit?