While Agent Rountree and Fatima are searching for Kilbride, who has been MIA, they are ambushed and learn that every member of the team has a $200,000 bounty on their head via the dark web. The NCIS team must save Agent Rountree and find Kilbride while every cartel, hit man, gang and psychopath hunts them down. The crossover starts on NCIS S20E10 Too Many Cooks (I) and NCIS: Hawai'i S02E10 Deep Fake (II).

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.

The mole has once again compromised the NCIS team as planted evidence results in the arrests of Callen, Sam, Granger and Deeks, on the day Under Secretary Duggan (Jackson Hurst) returns for Hetty’s resignation.

NCIS Special Agent DiNozzo partners with the NCIS: Los Angeles team to search the city after his prisoner escapes custody on a flight from Singapore to Los Angeles.

Deeks is arrested and interrogated in connection with the murder of his former partner, while the team tries to prove his innocence.

Callen and the team try to save a child in imminent danger who has been brainwashed by a terrorist cell. Also, Deeks and Kensi discuss having children.

After Sam's wife, Michelle, is taken from her home, the kidnappers demand the prison release of Tahir Khaled, Sam's arch nemesis, in exchange for information on her whereabouts.

The NCIS: LA team continues to search for new evidence to prove Kensi Blye’s innocence after a private meeting involving her deceased father’s sniper unit turns deadly.

Kensi and Deeks are sent undercover as married couple Melissa and Justin when evidence points to a Russian sleeper cell in a suburban neighborhood.

Sam receives a distress code from Aiden saying that his school is being taken over by an extremist group.

Hetty goes rogue, leaving the NCIS team completely in the dark, and the mole kidnaps one of the agents.

As the team races to save Kensi from Ferris/Sullivan, they find themselves questioning who they can trust when old faces resurface.

Following the kidnapping of Sam's wife, Michelle Hanna, Sam goes rogue from the NCIS team and attempts to stop his arch nemesis Tahir Khaled from ever targeting his family again.

Gravely injured and unable to communicate with the team in the U.S., Callen, Sam and Kensi, with an unconscious Deeks in tow, search for a safe way home as a cartel boss places a “dead or alive” bounty on their heads. Also, Mosely and retired Navy Admiral Hollace Kilbride beseech their contacts in Mexico and D.C. for assistance with their missing colleagues

After Anna Kolcheck escapes from prison with her cellmate, Callen and the NCIS team assist with the investigation and search for her whereabouts.

Akhos Laos , a former black ops agent originally recruited and trained by Hetty Lange, returns to seek revenge on Hetty for the life she introduced him to, on the 250th episode

Hetty's sudden resignation prompts Callen and the NCIS team to investigate the reason why she would disappear in the hopes of tracking her down.

The team investigate an arms dealer but are interrupted as the suspect's building is overrun by terrorists.

Callen, Sam, Kensi and Deeks join Hetty’s team from the Vietnam War, Sterling Bridges, A.J. Chegwidden and Charles Langston, in a dangerous and off-the-books rescue mission to save Hetty from her captors in Vietnam. Also, Mosley calls in Nell’s sister, homeland security specialist Sydney Jones, to assist the team in Los Angeles with processing evidence connected to Hetty’s time in Vietnam.

The NCIS team works with the Global Criminal Tribunal when a Syrian seeking justice, David Sarraf, is brutally attacked while delivering evidence that would prove chemical weapons were used on civilians. Also, Kensi stays at the crime scene and comforts Sarraf who is pinned behind a vehicle.

Callen and Sam work with Navy Captain Harmon "Harm" Rabb, Jr. (David James Elliott) to locate a group of ISIS sympathizers aboard the USS Allegiance. Also, Hetty enlists her friend, Lieutenant Colonel Sarah "Mac". Mackenzie (Catherine Bell), to help obtain information from a Russian diplomat.

Deeks' morning routine is disrupted when he is shot during a convenience store robbery, leaving the NCIS team to investigate whether he was the assailants' intended target.

The Special Projects team travels to Romania to search for Hetty, while delving into the history of the Comescu crime family, and their connection to Callen.

With Assistant Director Granger critiquing every move, the NCIS team must track down a chameleon-like killer who has evaded law enforcement agents, including their very own Special Agent G. Callen, across several countries.

The L.A. team is drawn into a deadly mind game against a master criminal motivated by Revenge.