The team investigates the murder of a Marine who had top-level security clearance, and the corpse is missing a hand.

A Navy SEAL imposter's death gives the team a lead on a missing canister used to make deadly bombs.

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.