When Charles Darwin finished The Origin of Species, he thought that he had explained every clue, but one. Though his theory could explain many facts, Darwin knew that there was a significant event in the history of life that his theory did not explain. During this event, the Cambrian explosion, many animals suddenly appeared in the fossil record without apparent ancestors in earlier layers of rock. In Darwin's Doubt, Stephen C. Meyer tells the story of the mystery surrounding this explosion of animal life-a mystery that has only intensified. Meyer argues that the mysterious features of the Cambrian event are best explained by intelligent design.