In order to hunt down the brutal murderer of a grifting seducer, Castle and Beckett must investigate New York's elite. Meanwhile, Castle plans to surprise Beckett on their one-year wedding anniversary.
Beckett and the 12th Precinct look into the murder of an English as a Second Language student. When the victim's class won't talk to the police, Castle goes undercover as a French Canadian immigrant and learns the victim was more than he seemed.
After an armored car driver is killed and some of the money it was carrying stolen, details of the heist start to ring a bell for Esposito regarding a previous theft of gold coins nine years earlier. Also, Beckett officially moves back in with Castle but is starting to feel that Castle's home network AI, Lucy does not have as much love for her as he does.