NCIS season 23

Parker goes to extremes to apprehend Carla Marino, to Vance's objections. Flashbacks show Parker's troubled youth and his estranged sister Harriet (Nancy Travis), now a Navy Vice Admiral, unsuccessfully trying to get him to change his ways. Parker's quest for revenge culminates in him stowing away on the ship Carla is on, and Harriet being forced to give an order to fire a bomb at the ship, realizing at the last second that Parker is on it.

The ship is detonated, but not by Harriet's missile. Marino had put a doppelganger on the ship to fake her death and kidnap her granddaughter to bring her into the crime ring. Parker, who had escaped the ship himself, discreetly works the case at Gibbs' old cabin alongside McGee, while the team works to rescue Marino's granddaughter. Meanwhile, Palmer discovers Marino may not have been the true killer of Parker's father.

Torres and Knight work with night shift agent Dale Sawyer (Zane Holtz) on a blackmail case, and Torres begins to experience supernatural occurrences.

The team investigates a Marine suspected of kidnapping the wife of a high-ranking official, and Knight discovers the wife might be a victim of domestic abuse.

When an inmate who had three weeks left until parole escapes prison, the team reopens one of Gibbs and Franks' unresolved cases. Meanwhile, the team puts together a time capsule.

Note : This episode concludes a crossover event that begins on NCIS: Origins season 2 episode 5.

While McGee releases a new book under his alias Thom E. Gemcity, the team investigates a murder which intertwines with McGee getting kidnapped by a woman making a desperate attempt to get justice for her deceased son.

Parker clashes with a priest when the team investigates the death of a Navy SEAL. Meanwhile, Jimmy admits his findings from the investigation into his mother's burial, all adding to Parker's pent-up grief and anger.

The team assists the Secret Service when a man is shot by the vice president's house. Meanwhile, Vance instructs the team to be shadowed by an AI chatbot whose input leads to some tension between Jimmy and the rest of the team.

The team assists Parker in his investigation into his mother's passing, and Parker discovers that his mother (who had been helping a mother and daughter get away from her abusive husband) was murdered by the man, a dirty cop who falsified the report that gave Parker the belief she had perished in a drunk driving incident. Meanwhile, Knight is given her first ELITE task by Vance: track down former NCIS agent Eleanor Bishop, who has since become a wanted fugitive. The episode ends with Bishop observing the team from her car in the distance.

Knight and NCIS: Elite are tasked with arresting Ellie Bishop after Bishop's hacker team is accused of leaking classified material. Bishop asks her old NCIS colleagues to help prove her innocence. During the case, Torres confronts Bishop on her sudden departure.

Note: Gary Cole does not appear in this episode.

When an Army major and former informant of Knight's barricades himself in an ammunition storage, he says Knight is the only one he'll answer to. Knight clashes with Army CID over whether or not he committed a murder.

Note: Brian Dietzen does not appear in this episode.

When a murdered Navy drone pilot brings one of McGee's exes back in his life, he is stunned to discover he has a long-lost son. Meanwhile, while preparing for their weapons recertification exam, Parker confronts Vance for supposedly not having the team's back. Vance reveals he's concerned over the fact the DOD might fold Army CID into NCIS due to budget cuts. Vance later stuns Parker and says NCIS is the agency being shut down.

When the son of a Marine that Gibbs once helped comes to NCIS in desperation to aid his sister, the NCIS team, now fractured due to the agency being shut down, reunites off the books. As Vance details the case's timeline to a mysterious individual, he also relays how the agency's history has positively impacted the lives of the public, every member of the team, and himself, despite many personal sacrifices. Vance comes to realize that during the case, he was fatally shot, and the mysterious man is in truth, the late Dr. Mallard (Adam Campbell). Vance also learns that after his death, the team solved the case and NCIS was able to reopen. Accepting his death and that the agency, the team, and his children will all be fine, Vance tearfully reunites with his late wife, Jackie.

Note: Final regular appearance of Rocky Carroll as Leon Vance.

During Fleet Week, a stolen MPD squad car case turns fatal after a stabbed sailor is found in the trunk. Meanwhile, Parker struggles with leading the team without Vance’s guidance.

After a Navy captain is murdered on a museum vessel, the team begins a Da Vinci Code style investigation looking for lost treasure that was worth killing for.

Note: Diona Reasonover does not appear in this episode.

A Navy lieutenant reappears six months after her plane disappeared, and the team discovers the crash wasn't an accident. McGee helps the lieutenant deal with her trauma by telling of the time he was held hostage.

With most of NCIS away and the mainframe shut down for a midnight upgrade, Kasie and a skeleton crew are left in charge of the reboot. Things get dangerous when someone kills a member of the “Tech Trolls.” Sam Hanna, who’s visiting during a flight layover, steps in to help find the murderer. Kasie later says she’s the reason the Tech Troll is dead.

Note: Sean Murray, Wilmer Valderrama and Katrina Law do not appear in this episode.

Continuing from the last episode, Kasie is framed for murder with her own self-developed biometric program. Sam Hanna helps the team find the real suspect and meets Kasie's ex-girlfriend in the process.

As Parker appears for the trial of Wayne Rogers-the corrupt Army CID director who was complicit in the murder of Vance-the team finds out that he has tried to make a deal with the Department of Justice. As Rodgers is put into WITSEC until the deal is approved, things get murky when Harriet Parker appears to have been given sensitive missiles for Venezuelan cartel members with Rogers's help. Rogers escapes and is apprehended with those missiles, but again put into WITSEC after he calls the Department of Justice. As Rogers is being transported by the US Marshals, the team gets news that he was shot dead by a sniper at 4500 ft, which leads them to suspect Gibbs. Harriet visits Parker's home and as he mentions cooking salmon received from Alaska, she suspects him to be complicit in Rogers's death.

Kayla Vance's involvement in a fatal coffee shop bombing investigation is under fire by Gabriel LaRoche, who discovers Leon had been funding it with dirty money. The team discovers the bomber was inspired by a book and the bomber's father attempts to kill the author, but Kayla talks him down. LaRoche drops the investigation and makes plans to become the new Director of NCIS. Meanwhile, McGee's son, Mateo, applies for an internship, but Torres discovers it to be false and confronts him when a gunshot goes off.

Note: Rocky Carroll reappears as Leon Vance in this episode.