Born in a Mission in China, Lucy Waring finds herself with fifteen small children to feed and care for. How she tackles this heavy task leads to her being thrown into the grim prison of Chengfu, where she meets Nicholas Sabine - a man about to die. He asks her the same cryptic riddle that Robert Falcon, another 'foreign devil', has asked her only the day before, and the mystery of this riddle echoes through all that befalls Lucy in the months that follow, when she is brought to England and tries to make a new life with the Gresham family. Unused to English ways, she is constantly in disgrace and is soon involved in the long and bitter feud between the Greshams and the family who live across the valley in the house called Moonrakers.

There is danger, romance and heartache for Lucy, and there is mystery within mystery as strange events build to a point when she begins to doubt her own senses. How could she see a man long dead, walking in the misty darkness of the valley? Who carried her unconscious into the labyrinth of the Chislehurst Caves and left her to die? It is not until she returns to China, a country now at war, that Lucy finds amid high adventure the answers to all that has baffled her. It is here, too, at the darkest moment when all seems lost, that she at last finds where her heart belongs.