In 1924, the Galway family - Robert, Maggie, and their children, Liza (12) and Gerry (9) - move to live on Erraid, a tiny, causeway island off the south tip of the Hebridean Isle of Mull. Robert is taking up a new post as one of the keepers on the lighthouse called Dhu Artach (Gaelic for Black Rock), some twenty-four miles out in the Atlantic. Six lighthouse families live on Erraid and there is a small school for the gaggle of children there. Theirs is already a dysfunctional family: Robert is a violent, abusive father; and Liza often struggles to stand between him and their gentle mother. Liza's difficulties increase on Erraid when the schoolteacher there, Miss Joan Dow, shows an unhealthy, obsessive interest in young Gerry. Then Liza discovers that Robert and Miss Dow appear to be embarking on an illicit relationship. Torn between loyalty to her mother and fear of her father, not to mention her own childish preoccupations with school, friends and her great love of reading, Liza is drawn into a spiral of deception, guilt and terror. She learns of a 17th century Jacobite legend: Lady Maclean of Duart Castle on Mull fled from Cromwell's soldiers with her nine-year-old son and reached Erraid with them in hot pursuit. Desperately, she set sail and was soon caught up in the strong tides that prevail there. Her boat was shipwrecked and she was drowned. Her body was recovered and buried in a graveyard nearby. However, the boy's body was never found. Legend has it that, every so often, her ghost walks on Erraid seeking her son, wishing to take him back to the graveyard with her. The relevance of this legend to the events that affect the Galway family gradually becomes apparent as the dramatic, suspenseful story unfolds. In the bleak but beautiful landscape, the legend combines with Jacobite history, Druidic myth and Joan Dow's mental instability to create a plot which escalates to a terrifying climax. In 2005, Jen, a distant cousin of Liza, stumbles across one of the threads of the story whilst on holiday on Mull. She resolves to find Liza, if she is still alive. When she does find her, Liza, now 94, recounts what happened as 1924 turned into 1925: the story of The Ghost of Erraid. Tiny Erraid has two claims to fame, both related to the classic author, Robert Louis Stevenson. His father, one of 'The Lighthouse Stevensons', lived on Erraid for a number of years while two lighthouses were being built in the mid 19th century. The stones to build them was quarried on Erraid and taken out in small boats to the huge rocks upon which the lighthouses were built. Robert visited his father on Erraid during this time and saw that it was a causeway island, accessible on foot from Mull when the tide was out. This gave him the idea for one of the chapters in his novel 'Kidnapped': the young hero, David Balfour, is shipwrecked on Erraid and does not realise that he can cross over to Mull when the tide is out. He spends three miserable days and nights, alone, soaked and starving, before he realises that there is a causeway on the other side of the island. The connection with Stevenson's Kidnapped is a feature of this modern novel.