Georgian England, mid-eighteenth century. As a foundling the young Em Smith is brought to the Cheshire country home of the ambitious Waterland family, where she serves as a companion to their daughter, Eliza. But as they grow up, Em's position becomes uncertain and she is increasingly troubled by the mystery of her birth. When Eliza goes in pursuit of a husband and a fortune in London, Em finds herself implicated in a horrific crime and must flee for her life. Her frantic escape takes her across country and onto the high seas, where she is at the mercy of the enigmatic smuggler, Captain McDonagh. But there is a more potent force drawing Emily on: a spirit whose presence she has felt all her life, and whose irresistible design - be it malicious or benevolent - will force her onwards to a distant shore. There she will confront the astonishing secret of her origins.