In Afghanistan a terrorist avoids a drone strike, but a discharged Marine dies; G and company investigate; Eric and Nell learn about more unaccounted former servicemen; the foursome go to Dubai and beyond, where they work out everything.

Four men die in an explosion of an otherwise empty diner in Pasadena; all four took part in a program of the Office of Naval Intelligence; the fifth participant, who's someone else, survives; two more die; G and team figure out all of it.

A man dies in a deliberate hit-and-run incident; the victim was a staffer of a candidate for the US Senate; G and company investigate; Kensi goes undercover as the replacement for the vic; the team solve the puzzle and nail the bad person.

Sam receives a call at home. A former colleague is in trouble that might have connections to a past case.

A man stops an ambulance, kills the EMTs, stabs the patient, and removes an object from his chest; the victim was a civilian scientist working for the US Navy; G and Callen put the puzzle together and find both the killer and the object.

A retired CIA agent dies when a lighter explodes; G and company investigate because Hetty requests the case; the fearless foursome check out high-priced call girls and more, and they defy orders, but they find the truth and the bad person.

An NCIS agent dies aboard an aircraft carrier at sea; the fearless four, undercover, fly to the ship, where they meet even more problems, but they eventually solve the crimes; Hetty joins them for Christmas underway; Nell catches Eric.

At 03:06 Deeks receives a call from a woman, Jenny, in two of his past lives; she tells about a ring stealing luxury SUVs and shipping them to the Far East; Jenny disappears; the team solve the puzzle, grab the bad guys, and rescue Jenny.

A routine traffic stop turns deadly, and leads the team to a terrorist plot.

In Mexico a US joint team makes a raid to capture the head of a drug cartel; due to a leak the team walks into an ambush; Granger tasks the gang to pinpoint the breach; they go undercover, find the leak, grab the head man, and rescue Nell.

Dean, a fugitive terrorist who disappeared in 1973, stumbles in from a woods, collapses, and dies of a stab wound; G and company investigate; the team find the pieces and fit them together; they find also explosives and one more bad guy.

One Russian kills another in the LA area; G and Sam quiz Arkady; Sam and Michelle go back undercover for the CIA; Sam lands in jail, and Hetty leaves him there; Greshnev dies, and Sidorov disappears; Hetty says that this is far from over.

In Idaho someone executes a Marine gunnery sergeant with a pistol; two days before in Los Angeles someone used the same weapon in the same way to kill an Indonesian man; the LA bunch collaborate with an NCIS mobile team. [Continued.]

The G gang and the Red Team continue to pursue Spears and other bad guys; attention turns to a big player in illegal immigration and a man with a red scarf; Hetty sees that Spears is not the executioner, then the teams catch the right one.

During a birthday celebration, 2 sailors and a dancer are poisoned in a bikini bar. When a radical Muslim group appears to take credit for the attack, the team must determine whether there is any truth to the claim.

Nell reports the death of the kingpin of a Mexican drug cartel in a police shootout; the body of the victim disappears from the morgue as soon as it arrives; G and company investigate the possibility of a leak, and they discover the truth.

Gunmen stalk and attack a woman, who disappears; three others die; Hetty cryptically assigns G and company to investigate; Hetty finds the woman, an NCIS agent undercover; the team catch the bad guys; G and Hetty discuss backgrounds.

A nuclear bomb explodes in a desert in Mexico; G and company investigate; Sam and Michelle go underground; G and Kensi go to Iran and bring back the Chameleon, who takes part in a complex deal to gain the two missing bombs. [Continued.]