The Girl on the Train is a gripping urban mystery fiction book written by Paula Hawkins. It follows the story of Rachel Watson, a woman who becomes entangled in a missing person investigation. Rachel, a daily commuter, witnesses something shocking from the train one day and becomes obsessed with solving the mystery. As she delves deeper into the lives of the people involved, she uncovers dark secrets and finds herself in danger. This thrilling novel explores themes of memory, obsession, and the blurred lines between truth and fiction.