Ed Maddux is an agent with the CIA.
The time period for Maddux's activities is the mid-1960's, the height of the Cold War and time of considerable escalation of tensions both in Indochina and in Europe. Major influx of troops to Vietnam are just starting in the former and in the latter the thoughts of a chance of loosening of the control of the Soviet Union on the Warsaw Pact countries is about to be destroyed. This means that the CIA is a very busy organization and has its hands in all sorts of pots.
Maddux when we first meet him has interest in none of that. In fact he has interest in not much of anything except his recreational love of rowing, something he picked up in college and which he still uses to exercise and something to do.
A graduate of Columbia University, Maddux is working at General Motors earning a modest salary. Despite what many would consider professional success, Maddux has grown bored of the mundane and is frequently looking for a way to "escape the doldrums of life". Plus his romantic life is non-existent. Recently divorced, his ex-wife is named Elizabeth, Maddux is "determined to never put himself in a position that could lead to heartache - his or someone else's. He'd been successful in maintaining his resolution, though he recognized that his avoidance of women was a major factor in doing so."
So this boredom would make him susceptible to taking an honor of a meeting with a CIA recruiter but it would not be enough to push him to take an assignment. That extra shove will come from the possible chance to solve a mystery that has bothered Maddux for some time.
Some time back, Maddux's father disappeared. What caused the vanishing has been in his mind since it happened. It was easy to feel that the man had died somewhere. But then the Agency recruiter, who from his manner of speech made it seem like he knew the father, made the statement at the end of the interview dinner that should Maddux decide to help on the matter at hand, "I know it'd make your father proud if you agreed." Not "would have made" but "would make". Present tense.
And so the nudge that gets Maddux to agree to help - just once. But it will not be just once and Maddux will have a new career.