Danny and Jackie investigate the murder of a high-end escort found floating in the river. Meanwhile, Frank vows to bring a killer to justice when a missing boy's remains are found from a case that he was emotionally invested in 25 years ago.

When an undercover counter-terrorism agent is shot, Frank assigns Danny to the case because he is the only officer he can trust given the victim's involvement with infiltrating a sleeper cell; however, Danny is sworn to secrecy as to not disrupt the police activity in that cell.