Harry Braham is an agent with American Intelligence.
Of course, when we first meet him he is a very young but about to get much older 22-year-old novice American pilot just arrived in France in the last months of WWI. He knew little about the world. He certainly did not know much about flying, having just been trained in the nascent Army Air Corps, and he definitely did not have experience with people trying to kill him and having to return the favor. He would learn quickly.
Also young and largely unsure of itself was American Intelligence, a catch-all phrase for a small department in the U.S. Army devoted to gathering information about the rest of the world because it had found itself very much in the dark about a lot of things as America arrived on the coast of France in 1917. A bit over two decades later and the newly conceived OSS would start to coalesce and a decade after that the CIA would come into existence but as Braham was surviving the bloody Great War, Yankee intelligence gathering was just learning.
The first of the recorded adventures of Braham relates the year or so he spent in combat and then the next decade and such he spent living and working in Europe. It sets up the environment in which Braham would operate in the later years but it also details in a fascinating way the changes that Braham will go through from the early days as a novice, inexperienced fighter pilot.
The subsequent records show his involvement as the world moves quickly towards war again. The Braham the reader can follow in those books is a much older, wiser in many but not all ways man. The shadowy world that Braham will be asked to visit is also older and a whole lot meaner.