Karl Baier is an agent with the CIA.
We meet him in the Fall of 1945 with WWII having ended and each of the Allied powers working in divided Berlin to grab up as much of German technology and brain power as it could. The quality of such was impressive and the goals for the national headhunters were to either get what could be gotten for the benefit of their country or to keep it out of the hands of the others. The biggest fear by the Americans was that the Soviets would get it all and be able to use it against the U.S. at a later date.
Baier was a Captain in the U.S. Army Intelligence "reporting to the Office of the Military Government, United States through its Office of the Director of Intelligence" and had been picked because he was first generation American, his parents having come to the States from central Europe. He spoke German fluently and had a strong knowledge of the culture.
Baier had been in the O.S.S. for some time and had been trained to take part in missions behind enemy lines but the war ended before he was given an assignment. When that organization was disbanded after the Japanese surrender, wanting to stay in the Intelligence field, he made the transition to Army Intelligence.
When, a couple years later, the remnants of the O.S.S. rejoined to become the new C.I.A., Baier was there to be one of its founding agents. The second adventure takes place a decade later with Baier now deputy station chief in Austria. Eight years of experience with the CIA had followed his time with the OSS and G-2 showing clearly Baier had experience in the job and knew what he was doing and his position as DCOS showed he was good at it.