Secrets of the Sea by Nicholas Shakespeare
Following the death of his parents in a car crash, eleven-year-old Alex Dove is torn from his life on a remote farm in Tasmania and sent to school in England. When he returns to Australia twelve years later, the timeless beauty of the land and his encounter with a young woman whose own life has been marked by tragedy, persuade him to stay. They marry, and he finds himself drawn into the eccentric, often hilarious dynamics of island life. Longing for children, the couple open their home to a disquieting guest, a teenage castaway, whose presence in their home begins to unravel their tenuously forged happiness.