After a diplomatic service van transporting an unknown package from the State Department is hijacked, the NCIS team must determine who committed the crime and what has gone missing. Meanwhile, Callen and Sam celebrate five years as partners, but face one of their biggest challenges when they go undercover for a case.

The team's investigation into the electrocution of a college student working on a classified Navy project leads them to his inquisitive daughter, who may be the key to accessing his work.

Sam resumes an old alias to bring down a major criminal kingpin; Callen and Anna's romantic night is interrupted when they are tasked with escorting a high-value prisoner to Los Angeles for questioning.