Castle (2009)

S3E6 3XK

The discovery of a stunning woman's body in an alley sends shockwaves through the city, as evidence suggests she has fallen prey to the infamous Triple Killer. Known as 3XK, this elusive murderer had previously haunted New York City four years prior before vanishing without a trace. Now, he has resurfaced. In a tense showdown, Castle and Beckett must outsmart 3XK and work tirelessly to prevent him from targeting more innocent lives.