Peregrine (Perry) White is an agent of S.A.C. Intelligence.
As the series begins, White is a virtually an expatriate living in Mexico, returning once a year to renew his visa to continue living south of the border. A former colonel with the army, White saw action and was wounded for his efforts, almost certainly in Korea though it is not mentioned. Now on disability pay and liking the simpler, cheaper life in Mexico, he makes his home there.
Prior to his military service, while he was attending university before the start of WWII, White had seen the rise of the local communist party in the colleges of his native Ohio and had reported it to the F.B.I., offering his services to track the activities of the key players. With its blessing, he joined the Party and became a key source for who was whom. He did so for no pay and no recognition.
Fifteen years and two major wars later, White has left all the excitement and danger behind for a fairly boring but safe life. His disabilities include wounds suffered in combat and a bad heart. He lives in Mexico because it is "warm and quiet" and because his best friend, named Paco Morado, lives there. That ends when a representative from the American intelligence community comes asking for help in breaking up a reported spy ring run possibly run by someone named Blanco who had a friend named Morado.
At the end of the first book, White is offered a job as an agent with a new department in Intelligence, this one operated by the Strategic Air Command. The second book, written after a lengthy gap of eleven years, takes place some time after the first with White working as an agent with S.A.C. Intelligence, stationed in Spain.