Sammy Mountjoy, artist, rises from poverty and an obscure birth to see his pictures hung in the Tate Gallery. Swept into World War II, he is taken as a prisoner-of-war, threatened with torture, then locked in a cell of total darkness to wait. He emerges from his cell like Lazarus from the tomb, seeing infinity in a grain of sand and eternity in an hour. Transfigured by his ordeal, he begins to realize what man can be and what he has gradually made of himself through his own choices. He determines to find the exact point at which the accumulated weight of those choices has deprived him of free will.