At all times, intelligence and counterintelligence were a secret activity; only a few were privy to their subtleties. We do not know all the secrets of the Roman intelligence services and will never know. But, nevertheless, thanks to the surviving works of ancient authors, as well as through a careful analysis of data from archeology, numismatics and epigraphy, the overall picture, and sometimes even individual specific episodes, can be presented quite clearly. Based on scientific data, the author sometimes comments on events, puts forward his own hypotheses and assumptions, but never resorts to fiction - the real history of intelligence and other secret services of Ancient Rome is much more interesting than any fiction.