In 1988, Philadelphia police officer Thomas "Locke" Lockhart, hungry to become a detective, begins tracking a serial killer whose crimes defy scientific explanation. When the killer mysteriously resurfaces nine years later, Locke's obsession with finding the truth threatens to destroy his career, his family, and possibly his sanity.

Three fiercely talented female homicide investigators work tirelessly to solve crimes while navigating the complicated demands of their personal lives.

Major real-life air disasters are depicted in this series. Each episode features a detailed dramatized reconstruction of the incident based on cockpit voice recorders and air traffic control transcripts, as well as eyewitnesses recounts and interviews with aviation experts.