One year after Darwin's explosive publication of The Origin of Species, sisters Anna and Beatrice Pentecost awaken to a world shattered by science, radicalism, and the stirrings of feminist rebellion. But society is not the only thing wracked by tumult and torment: Anna's anomalous love for Lore Ritter and her friendship with the freethinking and ambitious Miriam Sala carry her into areas of uncharted desire, while Beatrice is forced to choose between her beloved Will Anwyl and the evangelist Christian Ritter. Each is riven by inner contradictions, but who will survive when the sisters fall into a fatal conflict with one another?