The Innocent by David Baldacci

This assassin thriller has all the trappings required for a first-rate international terrorist mystery. It features a resourceful hired killer, a readily available and alluring young lady, an equally attractive, and hard-nosed female FBI agent, with a 14-year-old quick and alert young lady thrown in.
With most of the action centered in the Washington, DC, area, special agent Robie and teenager Julie search for the murderers of Julie's parents and the reasons for their deaths and possible connections with resulting killings that seemingly tie in with the loss of her parents.
Fast-paced, disjointed at times, but always provocative, and never quite sure who the good guys and gals are.