Botched assassination attempt in Belgravia forces NCIS to protect the Defense Minister's daughter, who is studying in the U.S. and smitten with McGee. Meanwhile, Gibbs investigates the death of the U.S. Marine who was killed in the bombing.

Discovers that one of its former investigative assistants found brutally stabbed to death was selling details for how to rob a warehouse full of valuable possessions belonging to a woman convicted of fraud. Meanwhile, a new special agent joins the office.