When a Marine known for his practical jokes is found dead on Halloween Eve, the NCIS team discovers that the victim's "good-natured" pranks may have inspired ghoulish retribution. Meanwhile, Ziva tries to adjust to her new role on the team.

When a United States citizen of North Korean descent is murdered, the secrets to classified software are thought to be lost until NCIS uncovers a suspect from Director Vance's past.

Since The League has SAMCRO members behind bars, the club must make new alliances in prison to survive. Alcohol, Tobacco and Firearms Agent Stahl uses this imprisonment to test Jax and Clay's relationship.

The two teams dig for a buried treasure on the beach. As a final result of the challenge, one team is sent home with loved ones while the other team stays at the ranch to train with their trainer.

Alicia and Will have only 72 hours to find the smoking gun that proves the train company, and not the three engineers, is responsible for the crash, thus securing the widows their pensions the company is holding back. Jackie and Alicia clash over taking the children to visit their father in prison.