Mac Ambrose is an agent with the CIA.
She has been one for 20 years, two decades of action as a field operative used to working on her own and far preferring it that way. Ambrose is known to a few of her superiors as someone who does not always play well with others. She is also known by these same people to be less than impressed with her superiors, suits who have not worked in the field like she has.
We do not learn much about Ambrose's early life. Well, nothing, actually, except that she had to have started with the Agency at a fairly young age because though she has been with them for two decades, she is still in prime condition, able to mix it up when necessary without too much suffering later. That would put her in her very late 30s or early 40s.This is conjecture arrived at by the fact that her first recorded adventure took place in Macao "12 years ago" and she had been in the service for almost a decade by then.
Most of that time, we learn from later reveals, she has spent outside the country on missions or lying low between jobs. As a result she has at times felt there were "gaps of knowledge about American pop culture" and while that does not bother her, it does make her realize what she has sacrificed for her choice of careers.
Ambrose works normally as a Non-Official Cover (NOC) operative which means she goes into the field as something she is not, hoping to do what she really is which is spy. Most of that time she has been "handled" by a controller in the Agency named Frank Odom and the relationship is one of mutual distrust and dislike. To Ambrose, Odom, who has never been in the field as far as she knows and has little in the way of a spine. This is particularly dangerous for the operative in harm's way when split decisions are called for. Since Odom has a lot of trouble in that department, Ambrose makes them herself and that invariably puts her out of favor with him and his bosses.
That fact that Ambrose gets the job done despite their 'wisdom' probably adds to their annoyance with her.