Cody is an assassin for the CIA.
She no longer wants to be but she is. She has fled on occassion to stop being one but she still is.
She is also a woman who is not afraid to use her body to get the job done. Actually, she is not afraid to use anything for with her training, anything within reach is a deadly weapon, including and perhaps especially her body. Her objections to her job are several, not least of which is she is tired of killing but also she is tired of being at their immediate call. Her life was not her own, her body was not hers, and her ability to make decisions for herself seemed a thing of the past. So she quit.
Cody had actually been initially recruited by the SIS. A British citizen who was attractive and smart but who lacked the financial resources to go to college, her life was in limbo as a young woman looking for a career when she was cornered at a party by an older man. The proposition he whispered to her was not the type she had expected. It was an offer to work for Her Majesty's government. With little better prospects she agreed. After a short indoctrination there, however, she and several other recruits were essentially "traded" to the CIA to appease relations after another high British intelligence officer defected. She was trained by the best to track, hunt, fight, seduce, and kill but mostly to survive.
For four years thereafter she worked for the Agency but her balking at some assignments grew more irritating until finally she was told point-blank, "if we tell you to shack up with Comrade X ... you'll do it." Cody didn't want to be a hunter. She didn't like being a killer. She refused to be a prostitute. She quit, but walking away from the Agency is not easy.
As the series progresses, she is learns the penalty for disobeying the Agency but survives and is finally able to get away, or so she thinks, but the puppermasters never really let go of the strings. To survive she has to take assignments in the private sector that have a lot of similarity to her previous employer. She might not be hired to eliminate a person but some of the assignments bring in people determined she not succeed and that leads to bloodshed.
It also leads to more than just the CIA trying to manipulate her. It seems everyone with whom she comes in contact are out to maneuver her into doing their dirty work, whether it is Britain's SIS or France's Surete. She hates it but cannot find a way out.
The last couple of adventures has Cody moving far away from her former work but her training and her instincts, as well as her talent for getting into the middle of trouble, have not left her.
Note: The fifth and last book in the Cody series was written 13 years after the penultimate one. The author had moved on to other topics and tales, writing a half dozen books about people other than Cody. Eventually, it seems, he found something else to say about her.