Robert Ludlum's the Bourne Ascendancy

Jason Bourne is working as a 'blacksmith' - hired by high-level government ministers fearful of assassination attempts. He is paid to impersonate these men at meetings in places of uncertain security around the globe, but when armed gunmen storm one such meeting, they're target is not the minister he impersonates, but Bourne himself. Kidnapped and transported to an underground bunker, Bourne finds himself face-to-face with a well-known terrorist who demands that Bourne carry out a special mission for him - one, that if completed, will have dire consequences for the entire world.