Sam Bradford is an assassin for the Agency.
This Agency is not in any way connected to the CIA, the organization which is most often associated with that nickname. The Agency that Bradford works for is ultra-secret as it does not officially exist. And it is ultra-scary as its primary purpose is handling wet work, a nasty euphemism for the elimination of enemies of the State; the state in this case being the United States but what makes the department so worrisome is the question of who determines someone is an 'enemy' and thus deserving of elimination. That is a quandary that Bradford will come to face.
But that questioning will not come right away. Bradford, a former Marine who likely would have stated a Marine as long as they let him but who suffered an injury that they decided should end that career. The separation was tough for a man of action like Bradford and that brought about severe depression which brought about a divorce from his wife which brought about even more depression. That was when he was approached with an offer to work for the Agency.
Bradford seemed ready-made for the job. He was now without emotional entanglements and ready to get back to something useful. After a lengthy period of intense training, including an impressive amount of study into the human anatomy and psyche, Bradford was set to become one of the best operatives the Agency had.
The next ten years would pass with him proving over and over he was very, very good at dispatching targets and since he had "no wife, no friends, and no family" and he lived "only for the job", he was certain to stay with them for even longer.
That is when he make what the Agency would consider a major mistake: he thought for himself. Agents like Bradford were not supposed to do that.
The "Rules" mentioned in the title of these adventures are not Bradford's creation; they were taught him and his fellow operatives from the moment their training began. As the name indicates, there are "122 Rules of Psychology" and these rules are designed to keep the agent alive and functioning and make it easier to get the job done.
The large number of them might seem excessive but each one is extremely simple to understand, remember, and follow, starting with the very first one: Rule #1 - Keep it simple.
Not all the Rules are explained in the adventures but a nice amount of them are and each one is very intelligent and reasonable and obviously helpful to the operative.
Three consecutive one are very straightforward and very true and worth mentioning here:
Rule #45: Frustrated people do not think clearly.
Rule #46: Angry people do not think rationally.
Rule #47: Furious people do not think at all.