Sam fears for his family’s safety when his wife is called to resume a former CIA cover after a case suggests ties to the infamous Sidorov and his stolen nuke.

Callen embarks on a secret project, leaving Sam and the entire team in the dark. After Hetty demands his operation be shut down, the team is tasked with locating Callen before he finds himself in over his head.

In order to locate Arkady in Russia, the NCIS team goes undercover with his daughter, Anna, at a gala in Los Angeles to gain access to the Russian Consul General’s computer.

Callen pursues every alternative when the Diplomatic Security Service apprehends his father, Nikita Aleksandr Reznikov, as part of an exchange for two American photographers being held hostage in Iran.

After months of planning, the NCIS family celebrates the wedding of Kensi and Deeks. Also, an old acquaintance, Anatoli Kirkin, pays Deeks a surprise visit on his wedding day and he isn’t alone.

When Callen goes to the National Counterterrorism Center on the pretext of interrogating a Russian asset from the crashed plane case he investigated months earlier, the tables are turned and he is detained, accused of being a Russian agent.

Callen and the team discover that Anna is being held by a group with ties to Anna's upbring and must rescue her before she is forcibly returned to Russia. Also, Admiral Kilbride makes Nell a serious offer.