Jacob Bell, a Navy contractor, is murdered, and NCIS gets invited in by NOPD. The killer garroted him from the back seat of his car. Jacob has a second family in Gulfport, Miss., as Jacob Landry. Sebastian and LaSalle find a secret surveillance room and armory in the Gulfport home. They set off a self-destruct mechanism which destroys the room but Sebastian saves a laptop. Jacob was a sleeper agent, likely Russian. Patton is having difficulty decoding Jacob's laptop. It does indicate Jacob was part of an ongoing operation in New Orleans. Jimmy got arrested for an open warrant from his former life. Pride promises Jimmy he will help him with the charge. Patton uncovers the location for a meeting set for Jacob. His two wives meet there, then get away from NCIS, with son Charlie driving the getaway car. Jacob was an assassin for the Russians. Pride goes home and finds Jimmy planning to skip town. Pride tries to convince him to stay. Patton tracks Charlie's car's GPS. They discover Charlie injured and Molly dead in a room with an airborne toxin, and Hannah locks herself in with them. Amanda and Jacob were Charlie's handlers, training him as an assassin. Charlie, who killed Jacob, tried to save Molly and her kids, who were about to be trained as assassins. Molly was an innocent who Jacob loved. Amanda is still trying to complete the assignment. Hannah and Charlie go to quarantine. Amanda goes after the kids, and Leah knocks out the social worker protecting them, and they leave with Amanda. The target is a Russian aid worker who witnessed a toxic-gas attack in Syria. Pride snags Amanda, but Leah tries to finish the hit. Pride gets the toxin bottle away from her. Jimmy shows up for a meeting with the D.A.