Thomas Hart and Grace Macaulay have lived all their lives in the small Essex town of Aldleigh. Though separated in age by three decades, the pair are kindred spirits - torn between their religion and their desire to explore the world. But their friendship is ruptured by the arrival of love. Over the course of twenty years, Thomas and Grace will find their lives brought back into orbit as a devastating story of passion and scientific adventure unfolds and Aldleigh's unique mysteries are revealed.