Rand Stannard is an agent with the DIA.
Codenamed 6-X, Stannard had served in Military Intelligence for several years before leaving the service and returning to college. As he was preparing to take his final exams from Law School, he was approached by a colonel with the Defense Intelligence Agency, then a very new organization, to assist in an assignment. He was chosen partially due to his experience but even more because a lady friend who was close to Stannard needed watching.
Reluctantly he took the mission and, to more his surprise than others, he was not bad at it. In fact, he was impressive enough to make the department decide to keep him on their list of available assets. Thereafter, he would work at his law practice as he would have done without the DIA work, and answer the call when the DIA needs someone with his qualification.
Stannard is just under 6' tall, blond, good looking enough to constantly attract the ladies, proficient at hand-to-hand, and speaks several languages fluently. He does not particularly like getting shot at or shooting at others but if given a choice, he would opt to be the shooter rather than the shootee.
"FOR ADULTS ONLY!" That is the opening blurb on the original paperback edition of this series. The adult nature of the books is quite limited, certainly no more than a contemporary Bond novel, indicating the tag was more attraction than warning. It is not a case of modern mores exceeding what was once risqué - it is more that some marketing agent wanted to spice up the covers. Stannard does entertain the occasional woman and there is descriptions of the entertainment but the books do not need any false advertisement.
The Stannard adventures also rivals the Beresford series by Agatha Christie as the longest time span between novels. Hers was 47 years. This series is 31 years.
There was 3 years between the 1st and 2nd, one year between the 2nd and 3rd, and 31 years between the 3rd and the 4th. Luckily, very little time has passed for Rand Stannard, leaving the readers to not know if the writer decided several decades later to write another one or if the 4th just sat unpublished for so long.