David Audley is an analyst for the British Secret Service.
He is one of those wonderful characters that is something different to a host of people. To most of his superiors he is a lucky guesser to be able to see past the evidence to get at the truth. To the people assigned to work for or with him, he is a devious schemer who tells people as little as possible. To those closest to him, he is a dedicated friend who can be counted on when the chips are down. And to his immediate superior, he is a genius.
As would be expected, he is all these things. Working as an analyst trying to sift the truth out of tons of incoming data, he has been able to come to the correct conclusion an impressive number of times. He doesn't like to tell too much to anyone, including those working with him, until he is fairly sure he is right. He usually is right, so his boss's conclusion is correct.
The adventures that Audley gets involved in are primarily counter-espionage ones trying to block the activities of those who come to England to learn what they shouldn't or do what they oughtn't.
The writing on this series is very good. It is also very British. The pacing is similar to a traditional British murder mystery with plenty of false leads to confuse the reader. There is often enough, though, brilliant insights given to make a befuddled reader grin and nod sagely as though finally I've gotten a hold of the situation.
As any good series should, this one has an interesting cadre of supporting characters. There is Audley's handsome young wife who goads him into some assignments he is loathe to take. Butler is an army officer attached to the Secret Service who often is assigned to Audley. Roskill is an air force pilot who is also seconded to the Service and must put his life on the line by Audley's orders. And Paul Mitchell is a researcher who reluctantly starts to help Audley as the series progresses. Each of these characters are almost as important to the series as Audley, making the series a lot more enjoyable than a one-man-show.