"The Alienist: Angel of Darkness" is a psychological thriller television series based on the novel by Caleb Carr. It is a sequel to the first season, "The Alienist," and continues to follow the investigations of Dr. Laszlo Kreizler, a criminal psychologist, and his team as they delve into a series of mysterious crimes in 1897 New York City. In this season, the team, including Sara Howard and John Moore, seeks to uncover the truth behind the disappearance of a young child and a string of murders. The narrative explores themes of mental illness, societal issues, and the complexities of human behavior, all set against the backdrop of a richly detailed historical period.