Beckett and the 12th Precinct look into the murder of an English as a Second Langue student. But when the victim's class won't talk to the police, Castle goes undercover as a French Canadian immigrant and learns that the victim was more than he seemed.

When a recruit officer at the NYPD Academy is killed, Beckett and the team go back to their old training ground to investigate. Meanwhile, Castle must reckon with a decision with profound consequences for him and Beckett.