Robert Ludlum's the Bourne Legacy - Eric van Lustbader

Jason Bourne is known and feared in the deadly world of covert-ops as one of the most highly skilled assassins for hire. Bourne, however, was merely an identity assumed by CIA agent David Webb, a personality implanted by the CIA to facilitate a dangerous operation, but one that threatened to subsume David Webb entirely. Years after the events of The Bourne Identity, Webb is no longer an active CIA agent and is now a professor of Eastern Studies at Georgetwon University, living a quiet life. Until one day he finds himself the target of an assassin nearly as deadly as himself and is framed for the brutal murder of his two closest associates and friends. Fighting for his existence against unseen assailants, as well as the full resources of the CIA who believe he has gone dangerously rogue, the Bourne identity asserts itself, leaving Jason Bourne in control. Now Bourne must use all his skills to stay alive as he battles against a determined assassin, the combined skills of the world's intelligence networks, and a shadowy figure in the background, manipulating events and people in a far deadlier and more dangerous game than any of them realize.