In 17th-century London, unnatural babies are being born, with eyes made for the dark and webbed digits suited to the sea. Sarah Davis is intimately familiar with such strangeness - having hidden her uncanny nature all her life and fled to London under suspicious circumstances, Sarah starts over as a midwife's apprentice to a member of the illegal Worshipful Company of Midwives, hoping to carve out for herself an independent life. But with each new unnatural birth, the fear in London grows of the Devil's work. When the wealthy Lady Wren hires her to see her through her pregnancy, Sarah quickly becomes a favorite of her husband, the famous architect Lord Christopher Wren, whose interest in the uncanny borders on obsession. Sarah soon finds herself caught in a web of magic and intrigue created by those who want to use her power for themselves, and whose pursuits threaten to unmake the earth itself.