Chief Petty Officer Elaine Dodd and her husband Spencer (along with their driver) are killed by a sniper while on a visit to Iraq.
Abby reveals that the bullets used in the killings were armor-piercing bullets designed for the U.S. military.
Bishop notes that a fire fight occurred two months previous to the murders, in an area close by, in which four prototypes for a specialized sniper rifle were being transported. It was reported that all four rifles were destroyed by an RPG. Only it turns out one of them was missing.
During the fire fight, some of the insurgents were creating a video.
Gibbs goes to Walter Reed hospital to interview one of the Marines involved in the fire fight, Marine Gunnery Sergeant Aaron Davis.
The killer uses Spencer's passport to gain entry to the U.S. He also transports the specialized rifle with him.
Abby notes that the killer wrote a series of numbers on the box. She determines that they represent airport radio frequencies. The team realizes he's targeting an airplane with the specialized rifle.
Abby notes that the airport radio frequencies match those used at Lafayette Field, in Virginia.
The insurgent's camera is located in Iraq, and footage reveals the face of the killer, a man named Matthew Cross. He used to work as sniper with the SAS.
Gibbs heads to the airport. The team identifies the target as an oil bigwig who has Middle Eastern connections. He works directly for the Iraqi oil minister. His plane is seven miles away from the airport.
Gibbs spots the sniper just as he's getting ready to fire on the plane. Gibbs shoots him dead.