Facing down mercenaries in Africa, Bourne witnesses the death of an art dealer named Tracy Atherton. Her demise triggers flash-backs to the killing of another young woman in Bali. A woman who entrusted to Bourne a strangely engraved ring - an artifact of such powerful significance, people have been willing to kill for it. Bourne is determined to hunt for the ring's owner and discover its true purpose. Bourne's trail leads him through layers of conspiracy to a vicious Russian mercenary, Leonid Arkadin, who, like Bourne, was a graduate of the Central Intelligence training program, Treadstone. A covert course designed to create ruthless assassins, it was shut by Congress for corruption. But before it was dismantled, it produced Bourne and Arkadin, giving them equal skill, equal force - and equal cunning. As Bourne's destiny circles closer to Arkadin's, it becomes clear their eventual collision is not of their own making. Someone else has been watching and manipulating both men. Someone wants to know, who is the more deadly agent? They are about to find out.