France, 1673. Desperate to save herself and her only surviving son from an outbreak of plague, the widow Charlotte Picot flees her village. But her son is kidnapped by slavers and she fears the boy has been taken to Paris, the terrible City of Crows. And so she resorts to witchcraft and summons assistance in the shape of a malevolent man. Meanwhile, a notorious criminal, Lesage, is unexpectedly released from the prison galleys where he has served a brutal sentence for sacrilege...