Deeks disappears while on an undercover assignment for the LAPD; Hetty offers help, so Callen and company lend a hand; Eric follows a trace to a Serbian bad guy; Deeks shows up and solves the case, and the team get him out of a tight spot.

In Cyprus an NCIS agent dies by murder; the killer lands at LAX, and G grabs and questions him and obtains information through a deal; G infiltrates the hit squad for the next lethal action; the team solve the puzzle and nab the bad guys.

The 14-year-old daughter of a Navy commander is kidnapped and buried alive. The FBI and the team investigate an incarcerated serial killer with an identical MO. Sam's past helps him empathise.

In downtown LA a lone armed woman seizes a Navy recruiting station; G recognizes her as his former partner while undercover for the CIA; she asks for his help and gets it; the team find the bad guy responsible plus the rest of the story.

Two men, a Marine reservist and a plastic surgeon, die by gunfire, and a woman disappears; Callen and company investigate; Eric and Nell provide clues, and the team go to a party, where they grab the bad guys and prevent any damage.

A sergeant first-class retires from the Army, the day he becomes a civilian he is kidnapped. When his tortured body is found, the team must determine the reason behind the extreme cause of death.

Intrigue and violence continue while several parties search for the "little black bloody book". The team investigates Cole's shooting and find a link to the murder of a cop during a traffic stop.

The team must piece together events when a recently discharged Navy lieutenant, and intelligence officer, with PTSD witnesses a shooting.

While Rose does an autopsy, two intruders blow away her assistant and steal the corpse and a van; she calls the Callen team, who investigate because of an apparent Navy connection. The team slowly figure out the puzzle.

The Pentagon discovers a breach after an online transfer of a file containing highly classified information. The team races against time and other interested parties to find the leak and retrieve the file.

Inmates initiate Moe by beating him inside a federal prison; Sam goes to him and undercover; Kensi and Deeks find a device and a plan; Hetty says there's more; an escape takes place, Sam loses someone, and a larger plan moves on. [Cont'd.]

Inside his pad by night G grabs a prowler, who works for Arkady, who gives G a tip; Kensi and her buds run a scam on a foreign businessman; G gets into a firestorm, but the rest of the gang show up and lend a hand.

Callen and Sam go undercover as motorcycle cops to investigate corruption within the force. When their contact is murdered they take on a job in hopes of catching his killer.

One of Sam's aliases receives an invitation to Yemen to meet Abdul; Hetty hopes that Abdul will lead them to Saadat, Abdul's brother, believed to be a leader of terrorists; G and Nate provide backup; the team support, and it all works out.

A Latino day laborer dies, and a lieutenant commander in Naval intelligence disappears; Callen and company investigate; G and Sam find evidence suggesting an assassination plot against a visiting Venezuelan politician; the team thwart it.

When a secure facility on a military base is compromised, Kensi goes undercover to find out what the world-class thief was intending to steal.

A major player in the private-sector aerospace industry dies inside a test chamber at his facility; Callen and company investigate; Eric goes undercover as an FAA inspector; a big bang occurs; the team grab the bad guys at a flea market.

An unidentified man dies after a beating and a burning; a specific radiopharmaceutical in the body implies a connection to a previous case; Callen and company grab the bad guy. Hetty resigns, disappears, and reappears in Prague. [Continued.]

Hetty turns up in Prague and proffers a message. G and Sam investigate; Eric and Nell help. G, Sam, Kensi, and Deeks go to Prague, find a lead, and follow it to Romania, where G has a flashback, and Hetty delivers the message. [Continued.]