Frances Bascom "F.B." Ivy is an agent with American Intelligence.
This very attractive redheaded female has been an operative in very good standing by the time we meet her in the first recorded adventure. Exactly which department of the government she is in remains a mystery to me but I can discern that since her employment takes her to a good number of foreign locales, the possibilities are narrowed down. Unless, of course, she worked for one of those "unnamed" agencies or, even better, "unknown" ones. What we do know is that she identifies herself as being a "special investigator" for the American government.
I made note of Ivy's initials above because the chronicler of her five adventures does that often in their telling, switching back and forth between it and her first name. The use of the full name is not uncommon, either.
Ivy is, as indicated, a very competent agent. She is also decidedly a very confident one. In one instance she is about to ask questions in a bar of some people who might turn out to be unsavory and she assures a friend, "I can take care of myself. If anyone gets hurt ... you can be sure it won't be me". Of course, while stating this, "a deadly looking automatic appeared in F. B. Ivy's hand as if by magic". That could help.
We are not told how hold Ivy is but the way older men act towards her, especially when they refer to her as "young lady", I would guess she is still in her mid to late 20s. She is also apparently in fine shape as seen by the reaction of more than one man when she has need of wearing a small bikini. Speaking of that apparel, she carries a blade of some unspecified length in a "pencil-thin cloth scabbard .. sewn into her bikini pants" and she practices "extracting the razor-sharp blade from the scabbard for hours on end under almost every conceivable handicap".
Ivy has a gift of languages, it seems, though exactly how many she knows is uncertain. For an assignment in Greece, she was able to converse with local residents in "fluent Greek". She also is "fairly proficient" in Russian.