In the wild highlands of southern China, a tribe of fisher folk must venture daily on to a fearsome river. Into their world of struggle and superstition arrives a young couple, John and Grace Gerrard. Raised among the teeming streets of Hong Kong and Canton, they now confront a culture so alien that it challenges their love - and their lives.
John is soon enthralled by the fisher folk, swept up by their dark gods and the invigorating dangers of the river. Meanwhile, Grace's missionary work only incites mistrust. Hoping to reconcile her Western religion with her Asian blood, she begins to develop an extraordinary theory . . .
But her insights provoke a murderous conspiracy. Parted by their enemies and the unforgiving river, John and Grace must find each other across the mountains and rapids of China's secret heart.