Stakes rise as the 12th Precinct matches wits with serial killers Jerry Tyson and Dr. Kelly Nieman. With the clock ticking, Castle and the team must crack the case before the killers claim their next victim.

After a man is mysteriously murdered in a park, Castle and Beckett team up with a competitive, high-powered female detective from Hong Kong, who has information about the victim. But as Beckett digs deeper into the case, she realizes neither her Hong Kong colleague nor the victim may be quite who they seem.