Having read about a third of the late Robert Ludlum's novels, I have a pretty good handle on how he operates. From what I can tell, the legendary suspense/thriller author has two kinds of main (male, always male) characters: The military/covert intelligence type, and the Average Joe who's being manipulated by the military/covert intelligence types.
1974's "The Cry of the Halidon," which I just finished, is one of the latter. It is not my preferred Ludlum style. In fact, "Halidon" is without question the worst Ludlum novel I've read; it took dogged determination to get through this rather messy, unfocused work. In the preface, Ludlum makes the rather candid admission that his wife basically had to drag him out of Jamaica, where the novel is set, so he would stop "researching" and get to some actual work. The book reads like it. Convoluted, lacking in intensity (a rarity in Ludlum novels, be they great or mediocre), and, as a result, difficult to follow. Leading man Alexander McAuliff has to be one of Ludlum's shallowest main characters, what with glancing hints at a murdered wife and time spent in the jungles of Vietnam. I won't bore with any more details of why this novel isn't worth your time.
No, I much prefer Ludlum's very non-Average Joe leads, such as Jason Bourne. It's through these characters Ludlum really expands his imagination; these characters routinely accomplish feats that make me wonder how the author even came up with/knew about the tactics of covert warfare, much less execute them in such engaging fashion. Names like Bourne, Beowulf Agate, and The Man from Lisbon, are etched permanently into my brain. If you've never read any Ludlum, "The Bourne Identity" is obviously a good place to start (the film adaptation has very little resemblance—oddly, both still come off well). But my particular favorite Ludlum novel is 1979's "The Matarese Circle," which includes some of the most compelling action storytelling I've ever read. To think Ludlum wrote this novel and "The Bourne Identity" in back-to-back years is a stunning achievement. The man was a machine.
So, if the excellent "Bourne" film trilogy got you thinking about reading Ludlum, trust those instincts. Just be sure to read the back of the book first—if it says anything other than "special agent" or "undercover operative," I'd keep looking.