Vietnam, 1963. A female Viet Cong assassin is trawling the boulevards of Saigon, catching US Army officers off-guard with a single pistol shot, then riding off on the back of a scooter. Although the US military is not officially in combat, sixteen thousand American servicemen are stationed in Vietnam 'advising' the military and government. Among them are Ellsworth Miser and Clovis Robeson, two army investigators who have been tasked with tracking down the daring killer.