NCIS, FBI and MI6 continue an international manhunt for an escaped British spy who is targeting current and former agents.

After Ducky is attacked by a man claiming to have information about his half-brother who died decades ago, the NCIS team searches for the perpetrator, as Ducky recalls the final emotional days he had with his sibling. Also, with the holidays approaching, Bishop and Jake discuss the future of their relationship.

The NCIS team re-examines an ambush on a group of Special Ops snipers in Iraq after an American couple is attacked in the same area six months later. When Gibbs discovers he needs the account of the lone survivor, Marine Gunnery Sergeant Aaron Davis, he tries to connect with the wounded warrior who is being treated for PTSD at Walter Reed Medical Center.

DiNozzo is reunited with his ex-girlfriend, Jeanne Benoit, when insurgents in Sudan attack a group of volunteer doctors, including her husband. DiNozzo and McGee travel to the crime scene for the joint murder and kidnapping case and join the search for the missing doctors.

The NCIS team, alongside the FBI and MI6, continue an international manhunt for an escaped British spy who has left one colleague fighting for their life in ICU.

After being shot, Gibbs fights for his life aboard a Navy hospital ship, while DiNozzo and Joanna travel to Shanghai to try and take down the Calling.

A Navy Public Affairs officer is murdered, and the victim's wife and mistress accuse each other of the crime. Meanwhile, Anthony DiNozzo Sr. helps a homeless woman who believes he is her father.

While visiting a pharmaceutical lab on a murder case, Abby is trapped with no communication to the outside world after armed men take over the building and hold everyone hostage.

The NCIS murder case of a retired Navy Lieutenant Commander forces Ducky to reveal his participation in a secret society that solves cold cases.

The NCIS agents’ personal plans are interrupted when each of them catches errors in a seemingly cut-and-dried closed case. Also, McGee and Delilah argue over the importance of not discussing work during dinner, while DiNozzo bores his date with shop talk.

In order to clear his name, a petty officer volunteers to be court martialed if NCIS agrees to conduct its own investigation after his murder case is dismissed due to a mishandled warrant. Also, Bishop and Jake discuss their marital problems.

When Secretary of the Navy Sarah Porter learns her daughter has been kidnapped, the NCIS team partners with the FBI to track the case, determine a motive and bring her home. Also, McGee’s childhood friend, NCIS Special Agent Valerie Page is in town to assist the team with advance tactics training

Doctor Cyril Taft experiences the rush of an NCIS case after he is assigned surgical duty to Gibb’s suspect and finds key evidence. Also, Dinozzo pays Jeanne Benoit a visit as he chases a lead involving doctors in Sudan.

Tony's identity is stolen by multiple perpetrators who go on to blackmail politicians.

When a 14-year-old foils a home invasion, Gibbs suspects the teenager is withholding pertinent details. Also, Director Vance and Senior FBI Agent Fornell travel to London as part of the ongoing escaped British spy case.

After a Marine is found murdered in Quantico hours after calling Gibbs to discuss a possible case, Bishop and McGee go undercover as a married couple to run surveillance on a Marine Lieutenant and his wife.

The Secretary of Defense calls on NCIS to help a sailor who is battling leukemia to locate a donor for a bone marrow transplant, after two of his siblings are killed in the line of duty. Meanwhile, Bishop returns home to Oklahoma for Thanksgiving.

The passengers and crew of a private plane traveling from New Orleans to Washington, D.C., are poisoned and the evidence points to Abby's brother, the aircraft's missing chef. The episode continues on NCIS: New Orleans S2E12 Sister City (II).

Gibbs and Senior FBI Agent T.C. Fornell unite after two British prisoners, including a former spy, escape and arrive stateside via a shipping container. Also, McGee is busy apartment hunting and determined to find out how DiNozzo purchased his lavish place.

Gibbs calls on the team to assist DEA Agent Luis Mitchell with a case that keeps going cold, but DiNozzo discovers there is more to Gibbs’ personal connection to the agent and his desire to help him succeed. Also, the team gossips about Gibbs’ new look after he replaces his standard military haircut and polo shirt for a modern cut and tailored dress shirt.

Vance partners with Gibbs and returns to field duty when a murder case is connected to a former NCIS agent he locked up for stealing evidence.

When a petty officer’s murder matches the M.O. of a local serial killer, the NCIS team must determine if this is the killer’s latest victim or the work of a copycat. Also, McGee and Delilah must learn to compromise before moving in together.

While investigating the murder of a seaman who was set to testify before a grand jury, the NCIS team uncovers the resurgence of an international human-trafficking ring. Also, McGee hopes to spend the night at a colleague’s home after a storm causes massive power outages in the city.

Four deep sea divers stay inside a diving chamber with a deceased body in order to decompress. The dead body belongs to a retired petty officer who died in mysterious circumstances. The NCIS team will try to crack the case from land while the divers spend four days with the body.