The story of Black is based on the true life story of Helen Keller. Michelle McNally (Rani Mukerji) who loses her eyesight and hearing a few months after birth and exists in a black world where she is isolated in the darkness of her own existence, trapped by her inability to see, hear and express.
She grows up becoming more and more frustrated by the black and dark world around her, making her a violent, uncontrollable eight-year old. Her parents, Paul and Catherine, are at their wits' end trying to control her, until one day the light shines through the end of the tunnel. Debraj Sahai (Amitabh Bachchan) enters their lives, an elderly alcoholic teacher for the deaf and blind, Debraj sees himself as a magician and is a disillusioned eccentric man.
He takes it upon himself to bring young Michelle into the light. He has harsh ways, very harsh ways actually though it is used for her long-term benefit. Through many good and hard times Michelle becomes much more tame and almost completely not aggressive. After many years with Debraj, Michelle changes her life completely in those years. One day Debraj leaves Michelle to her much regret. Eventually she finds him again though this time it is he who needs her help. The story ends with Michelle attempting to cure Debraj.
BLACK is the inspiring story of how Michelle transforms her life with Debraj Sahai's help - who she lovingly calls 'Tea cha' (teacher) and tries to achieve graduation in a regular university.