The Delphi Bureau (1972)

Glenn Garth Gregory possessed a terrific weapon: a photographic memory. This made him an easy recruit into the Delphi Bureau, a government intelligence agency answerable only to the President of the United States. Even though Gregory never really warmed up to the idea of being a spy, he was a good one, battling a number of nefarious foes and using his photographic memory to decode mysterious messages. His contact was a middle-aged Washington debutante named Sybil.