Beatrix Rose is a former agent with Group Fifteen.
That department is a highly covert part of British Intelligence existing to handle the jobs that MI5 and MI6 either cannot or, more commonly, do not want to handle. Elimination is the specialty of Group Fifteen and those in the know are quite familiar with just how good its top agents can be. The head of the department is known as Control, answering to the head of MI6 but empowered with a considerable amount of autonomy.
Agents in the field are designated Twelve to One with One being the most senior or the most deadly. Since the jobs these operatives are given carry a tremendous amount of danger, the death of an agent comes as no surprise and those higher in number move to the next slot.
Rose had been Number One for several years and her holding that position was well earned. She was cold and ruthless and incredibly cagey. She was able to maintain this composure because of an outlet she had in the private sector - she was happily married with a very young daughter.
Then she made a simple mistake of looking at something she was not supposed to see during an assignment to eliminate two Russian agents. She learned the hit was ordered by Control to cover up some profitable, and very treasonous, dealings he had been doing for years to feather his own nest. Control ruled her a threat and sent five of his agents he knew could be bought to kill her.
They failed but they did kill her husband and make off with her daughter. Rose was left in an impossible position. If she went after the girl, her daughter would be killed. If she stayed around, she would be killed, and probably the daughter as well. Disappearing was the only answer she could think of.
The series begins when Rose is hunted down by , himself a former Number One and also one with a huge reason to hate Control.
Rose is tired of hiding. She is tired of not having her daughter. She is tired of Control and his goons still living. She is determined to change all that.