In this immersive novel set in 1840s Britain and France, questions of identity probe at the essence of what it means to be human. A wet nurse goes by an assumed name but longs to know the identity of her father. A quarryman furtively extricates a remarkable fossil from an island off the Northumberland coast and smuggles it abroad to Paris. A sensational best-selling book triggers widespread argument and speculation—but its author’s name is a secret. Another book, roundly ignored, sets forth the principle that will become the centrepiece of Charles Darwin’s Origin of Species. All these threads—some historical, others fictional—converge and illuminate one another in unexpected ways in the climactic revelations of this brilliant story.