This novel narrates the story of Rachel, a depressed alcoholic woman who has been living at her friend's place in Ashbury for two years since her divorce. Every day, she takes the train from Ashbury to London for work. Her train stops at Witney station for a few minutes daily, where she observes a seemingly happy couple in their house through the window and becomes obsessed with them, as she lacks love in her life. But is the couple really happy? Are they hiding something? Is their life actually as perfect as Rachel perceives, or are her observations hallucinations caused by alcoholism? Read the novel to find out.