A Philadelphia police officer struggles with a lifelong obsession to track down a mysterious serial killer whose crimes defy explanation. —Netflix In 1988, Philadelphia police officer Thomas Lockhart (Boyd Holbrook), hungry to become a detective, begins tracking a serial killer who mysteriously resurfaces every nine years. But when the killer’s crimes begin to defy all scientific explanation, Locke’s obsession with finding the truth threatens to destroy his career, his family, and possibly his sanity. —Netflix In 1988 a police officer investigates a series of murders. The only thing connecting the victims appears to be the murder method. The police manage to piece together an image of the murderer from one of their would-be victims. Now the hunt is on. —grantss In 1988, in Philadelphia, Police Detective Locke and his partner Maddox hunt down a female serial killer. Locke kills her in the subway and the case is closed by his chief Holt without identification of the killer. In 1997, similar crimes happen and Locke and Maddox believe in a copycat. However Locke finds that the killer is the same woman he killed nine years ago. Locke becomes obsessed with the case along the years and Locke believes she travels in time in the opposite time-line. When the woman reappears nine years later, Locke is waiting for her.