The Ambler Warning: Robert Ludlum

On Parrish Island, off the coast of Virginia, there is a little known and never visited psychiatric facility where the government stores former intelligence employees whose psychiatric state makes them a danger to their own government.
One of these employees is former agent Hal Ambler. But there's one difference between Hal and the other patients - Hal isn't crazy. Hal pulls off a daring escape and now he's out to discover who stashed him here and why. But the world he returns to has changed. No one remembers him, there are no official records of Hal Ambler, and, when he first looks in the mirror, the face he sees is not his own...