
Naval Criminal Investigative Service Special Agent Leroy Jethro Gibbs leads a group of colorful personalities in investigating crimes -- ranging from murder and espionage to terrorism -- that have evidence connected to Navy and Marine Corps personnel. The team includes MIT graduate Timothy McGee, Ellie Bishop, who specializes in international threat assessment, charismatic and unpredictable Nick Torres, and forensic psychologist Jack Sloane. Dr. Donald "Ducky" Mallard brings his vast experience in forensics into play to help solve cases.

When evidence reveals a team member is a hit man's latest target, the team must search through old case files to determine who is seeking vengeance.

Vance assigns McGee, Torres and Bishop to COVID compliance duty at a foreign affairs summit, where they discover a link to another NCIS team's murder case.

While Gibbs attends the memorial service for a friend who was lost at sea, he discovers that the deceased has been hiding in a fallout shelter after his boat was attacked, and he swam to shore.

Evidence from the stabbing of a Marine sergeant leads Torres to meet his father, who left when Torres was a child.