Cornwall, 1917. After the death of his father, fifteen-year-old Simon Lysaght is sent to live with his uncle, Sir David Trevelyan, at their estate house, Trevelyan Priors. His uncle is an imposing man and Simon feels ill at ease in this large and forbidding house. On his first day he discovers there have been a number of family suicides and his cousin William, who is crippled and bed-ridden, warns him never to wander the corridors after dark. While exploring the grounds after a day of heavy snow, Simon discovers a track of fresh footprints in an enclosed garden, long abandoned and overgrows. Who do they belong to, and how did they get there? Simon can see no answer, until one day weeks later when he encounters a girl of his own age in the garden. They strike up a friendship, but doubts remain in Simon's mind. And when he discovers a sinister secret in his uncle's library, Simon is soon to find that Trevelyan Priors and its inhabitants have much to hide and more to tell than he can guess.