When a Russian bomber goes missing while flying over U.S. soil, Callen and Sam must track it down in the desert and secure its weapons and intel before the Russians on board destroy the plane; Hetty gives Nell a cryptic assignment.
The NCIS team is called to help find the missing star witness in the trial of a chief petty officer who Callen and Sam arrested for war crimes.
Nell sends Sam to meet an informant who plans to blow the whistle on a military secret; Kensi and Deeks debate whether or not to buy their first house.
The body of a murdered Navy reservist is found by thieves in the midst of a robbery, and NCIS must work with the burglars to find the killer; Kensi and Deeks struggle to decide if they are ready to make the leap and buy a house.
In order to get intel on a matter of national security, Kensi must come face-to-face with a sociopath who has been obsessed with her since she put him in jail years ago; Eric is desperate to keep Kensi safe, but he is forced to leave NCIS.
Before Christmas, Hetty assigns Callen the case of his former foster brother and his wife, who, upon reentry into the U.S., are framed for smuggling drugs across the border; Deeks is struggling with losing his job at NCIS.
The NCIS team's murder investigation of a man who sold military information leads to the abduction of a doctor whose cutting-edge neurotechnology could be developed into advanced weaponry; Callen tries to have an important talk with Arkady.
When the team investigates the murder of a man about to reveal the source of a counterfeiting operation, an old acquaintance becomes their prime suspect and reveals the true reason for her return; Deeks struggles during training.