Robert Ludlum's The Bourne Objective (Bourne Series #8)

Facing down mercenaries in Africa, Jason Bourne witnesses the death of an art dealer named Tracy Atherton. Her killing dredges up snatches of Bourne's impaired memory, in particular the murder of a young woman on Bali who entrusted him with a strangely engraved ring-an artifact of such powerful significance that people have killed to obtain it. Now he's determined to find the ring's owner and purpose. But Bourne never knows what terrible acts he'll discover he committed when he digs into th...