On the side of a mountain, in eighteenth century Japan, sits a man in perfect stillness as the summit erupts, spitting fire and molten rock onto the land around him. The man is Hakuin. He will become the world's most famous teacher of zen. This is not the first time he has seen hell. Hakuin's quest for truth will call on him to defy his father, to face death, to find love and to lose it. He will ask, what is the sound of one hand clapping? And he...