"The City of Glass" is a novel by Paul Auster that blends elements of mystery and existentialism. It follows the story of a writer named Daniel Quinn, who receives a phone call meant for a detective named Paul Auster. Intrigued, Quinn decides to take on the case, leading him into a labyrinthine investigation in New York City. As Quinn delves deeper, he encounters a range of characters and situations that challenge his identity and purpose. The narrative explores themes of isolation, identity, and the nature of reality, ultimately blurring the lines between fiction and life.