While Callen suspects Hetty of keeping disturbing secrets about his past and Joelle surfaces in her quest to capture Katya, NCIS must track down Russian informant Zasha Gagarin (Olesya Rulin) whose life is in danger. Meanwhile, Kensi and Deeks continue their efforts to expand their family.
NCIS takes the case personally when an LAPD officer's father, a beloved elderly Japanese American veteran, is the victim of a vicious hate crime.
Sam and Kilbride clash when a case involving an arms dealer responsible for the slaughter of ATF agents leads them to a well-connected colonel and friend of Kilbride, accused of supplying militia groups with guns. Also, Kensi and Fatima go undercover at a rehab facility to question the arms dealer’s girlfriend.
As Callen continues hunting Katya, Kilbride enlists NCIS help to find a truckload of stolen guns; the assignment becomes more challenging when their suspect, the son of a mob boss planning to sell the weapons, is found dead.
When an NCIS mission to protect a compromised undercover agent goes completely sideways, the agents are individually interrogated to find out what really happened; Kilbride must make a difficult decision.
Sam negotiates, and Roundtree goes undercover, when a man takes a busload of hostages and threatens to blow it up unless his daughter's war crimes are posthumously cleared.
The NCIS team investigates the apparent suicide of a Navy intelligence officer who leapt to his death after taking LSD. Also, while Kensi is away at the Mexican border, Deeks makes plans to redo the backyard without her input.
The NCIS team, joined by Special Agent Aliyah de León (Briana Martin), scrambles to find Kensi, when she is attacked and kidnapped by a mysterious militia group while helping a group of migrants cross the border. While captured, Kensi bonds with one of the migrants captured with her, a teenage girl seeking a new life in the United States.
The NCIS team, assisted once again by Agent De León, helps a U.S. ambassador search for her missing daughter, Gia (Caitlin Carmichael), a popular social media influencer, after she is kidnapped. The team is shocked when the kidnappers force Gia to ask her followers to raise ransom money and a counter-campaign of misogynists begins raising money for the kidnappers to execute her live on social media.
The NCIS team is called in when a civilian scientist working with the Marines on development of advanced radar technology is killed and the technology stolen. The team pinpoints the perpetrators as a white nationalist group attempting to bomb an immigrant center with explosives supplied by the Chinese government in exchange for the radar. Though the group is killed and a Chinese operative arrested, the technology remains unaccounted for. Meanwhile, Callen is confused when his doctor insists that
Kensi and Deeks are called to the USS Allegiance to help uncover the identities of the parents of a newborn baby found in the ship's cargo space. Meanwhile, Kilbride calls in former OSP team member Nate Getz for advice on helping Callen, who is frantically searching for Hetty after a United States drone strike on Al Qaeda occurs at her last known location in Syria. The two also discuss the Drona Project - the CIA operation in the 1970s run by Hetty that groomed young children, including a freshl
The OSP team is called in to investigate when an unidentified aircraft crashes into a Navy fighter jet from the USS Allegiance. The investigation turns on its head, however, when the UAP (unidentified aerial phenomena) is revealed to be a drone swarm purchased by the D.O.D. and operated by a rogue AI system that is testing its learning capabilities against the US Navy, the "greatest potential opponent" the system could train itself against. Meanwhile, Deeks and Kensi begin to prepare for their f
When DOJ Agent Lance Hamilton's partner is killed, Sam dons his previous undercover persona of "Switch" to find the culprit. Also, Kensi, Deeks, Roundtree, and Kilbride work to catch an aerospace engineer who stole classified Navy schematics.
NCIS investigates the robbery of a high-end art storage facility by going undercover as potential buyers on the black market, to find who is behind the stolen items.
Roundtree and his younger sister are pulled over by police and treated harshly in a clear case of racial profiling, leaving the OSP team enraged. Also, NCIS investigates the death of a Navy photographer who was assigned to document the building of a new weapons station.
NCIS investigates the kidnapping of Master Sergeant Boomer, a military working dog. Meanwhile, Sam looks to sell his boat so he can take care of his father who is suffering from Alzheimer's, and Callen meets with Nate to discuss the troubling series of recent events surrounding his life.
The team helps Naval intelligence officer Akhil Ali locate a fellow officer who went missing while recruiting foreign assets as potential sources of intelligence; Callen, with the aid of Nate, works to track a man he believes is the individual who trained both himself and Katya.
NCIS, with help from Sabatino, investigates the murder of a woman employed in the Navy's missile defense program and its connection to stolen Navy missile technology. Callen is pulled from field duty due to the deep fakes sent by Katya voicing scandalous messages to numerous individuals, including Kilbride and SECNAV; however, Callen uses the time to hunt for Katya. A strict social worker stresses out Deeks; Sam debates selling his boat.
The NCIS team works with DEA Agent Talia Del Campo to find a missing whistleblower set to testify against gun manufacturers marketing to drug cartels; the team is charmed when Eric sends everyone money with the instruction to buy something they each have always wanted.
NCIS investigates after two men are blown up by their own explosives while attempting to break into a military base; Callen wants to take the next step with Anna; Sam moves in with his father.
The OSP team scrambles to locate Callen after he falls into a trap laid by Katya and is kidnapped. With aid from Joelle and Anna, the team outsmarts Katya's deep fakes, psychological warfare, and false leads to rescue their leader. In the midst of the chaos, Joelle murders Katya and her ally in retaliation for losing her leg at Katya's hand.
The team hunts for a crew that robs a Los Angeles casino with military-grade power. Meanwhile, Kensi and Deeks learn that their adoption request for Rosa has been approved, officially making them foster parents. Following the case, the team surprises Rosa with a beach party, where Callen, after hearing Anna's desire to live the rest of her life with him, finally proposes to her.