The Bourne Identity - 1980
But Jason and Marie will have not time and peace enough to work Bourne's memory out as they would like too, the CIA and Carlos "The Jackal" are very corcerned about this "lost son / counter part rival" and will do whatever it takes to find him and if were necessary, eliminate him.
Keep an eye on: the well-known style of Ludlum to describe all the scenes and weaponry. It worths to mention all the flash-backs that Jason has from his multiple previous identities.
The Bourne Supremacy - 1986
A crazy hunt will take us to China were Marie St. Jacques will take a key role whilst Bourne runs for his life at the same time that he wants some heads to fall.
Keep an eye on: the time line offered by Ludlum, the amazingly well elaborated strategies played by CIA, Bourne and Marie on the different situations they will face.
The Bourne Ultimatum - 1990
Russia and Caiman Islands will be the scenario for a great battle where to titans will face for their final challenge. The skills are the same, but their youth is gone and strategies must be better calculated as any little mistake can be lethal.
Keep an eye on: all the additional characters allied to each bands and the usual high detailed action sequences written like only the fiction masters can do.
All of them: A must read.