NCIS investigated the death of a petty officer, who was killed by a Navy drone strike. Hollis Mann, an ex-girlfriend of Gibbs, joined the team as part of a NCIS-Department of Defense team-up for the investigation. They discovered that the terrorist Benham Parsa was behind the killing, and that it was done as a test run for a larger target: a Conrad Institute dinner gala, where McGee's girlfriend Delilah was to be honored for her work in counter-terrorism. Parsa's attack was successful: four people were killed, and many were injured, including Delilah. Mann and Gibbs found the terrorists' base of operations and managed to kill two of them. Parsa escaped in a getaway car.