An explosion at a D.C. event that results in a casualty connected to the agency changes Parsons’ perspective on Gibbs and the NCIS team. Meanwhile, without badges, DiNozzo and McGee investigate the case as civilians, despite the case’s dangerous ties to each of them.

The NCIS team must rely on Twitter for a case involving a missing Navy Lieutenant. Meanwhile, McGee misplaces his badge but withholds the information from Gibbs and the authorities.

Gibbs and McGee travel to Afghanistan when a murder case leads them to an Afghan women’s shelter Mike Frank’s secretly supported for years.

DiNozzo returns to his Baltimore Police Department days when he sees a felony suspect from a 15-year-old case at the NCIS crime scene of a murdered Petty Officer.

The Coast Guard Investigative Service works with the NCIS team when an explosion occurs on an oil rig; a mysterious prankster targets the team.

After Gibbs leaves mid-case to help his father reconnect with a former war pilot, Tony and McGee argue over who should run lead on the team’s investigation into the murder of a Marine Sergeant.

The team is forced to take another look at a hit-and-run murder case; McGee becomes suspicious of Tony's unusual behavior.

After discovering the Secretary of the Navy was bugged during a confidential briefing, NSA Analyst Eleanor “Ellie” Bishop, who predicted the security breach in exact detail two years ago, partners with the NCIS team on the case.

Complications arise when the NCIS team discovers a link between a murder victim and the current boyfriend of Gibbs and Agent Fornell’s ex-wife. Meanwhile, NSA Analyst Ellie Bishop adjusts to joining the NCIS team.

After a mysterious illness strikes children from military families, Gibbs and the team investigate the cause. Meanwhile, Abby and Jimmy partner with the Naval Medical Research Center to determine the strain of illness, all in hopes of delivering a cure before the holidays. Also, Director Vance struggles with forgiveness as his estranged father-in-law makes a surprise visit to his home.

When a stolen drone is linked to the elusive terrorist Parsa, the NCIS team partners with the Department of Defense, including Gibb’s former girlfriend Hollis Mann, to track down the device before it is used for a large scale attack. Meanwhile, McGee hesitates to ask for time off to attend a black-tie gala honoring his girlfriend.

In an effort to find the terrorist Parsa, Gibbs and the NCIS team track down one of his cohorts using evidence from the drone attack. Meanwhile, an emotionally shaken McGee struggles with the ramifications of the incident.

A port authority officer's murder reveals a possible location for Parsa; Bishop reveals a past connection to the terrorist.

After uncovering faulty bulletproof vests in a truck filled with stolen U.S.M.C. merchandise, the NCIS team attempts to locate both the source and any vests that had been shipped to military personnel overseas.

Someone winds up dead when DiNozzo confronts a man impersonating a Navy officer; DiNozzo's father needs to share a secret with his son.

After a bomb detonates in the dressing room at a military charity concert, the NCIS team must determine if the target was a washed-up ‘80s rocker or if the bomb was part of a larger scheme. Meanwhile, Jimmy prepares for fatherhood

When a former NCIS agent's body washes ashore in New Orleans, Gibbs reunites with NCIS Special Agent Dwayne Cassius Pride (Scott Bakula) to determine if the murder was politically motivated or related to a well-known case.

Gibbs and Special Agent Pride chase leads in New Orleans after evidence points to a copycat of the infamous Privileged Killer. Meanwhile, Bishop sends DiNozzo a special souvenir from the Crescent City, as DiNozzo, McGee and the FBI continue to track political connections to the case from D.C.

After returning to her job at the Department of Defense, McGee’s girlfriend Delilah finds a break in a controversial case, prompting her to turn to the NCIS team for help. Meanwhile, McGee talks to DiNozzo about whether he should ask Delilah to move in.

After a Navy officer is found dead on a rural road, the NCIS team must ascertain if the murder was the result of a bar fight or because he knew too much about an attack on a fellow female officer. Meanwhile, DiNozzo and McGee start a juice cleanse to purge their bodies of impurities.

When a Marine photographer disappears prior to providing his testimony in an Army court-martial hearing, the NCIS team investigates both the murder he witnessed as well as his current piece on military veterans who are homeless in the D.C. area. Meanwhile, Abby tries to help a young homeless woman reconnect with her family.

Director Vance gives DiNozzo a special assignment to bring home an Admiral’s daughter from Paris, but he must turn to his NCIS team for help after he enters a controversial crime scene.

The NCIS team investigates whether a fire on a U.S. Navy ship that served as a secret detention site for indicted terrorists was accidental or an intentional diversion for an escape. Meanwhile, Gibbs travels to his childhood home following news of his father’s passing.