Kendra Shaw is an agent with New Zealand's Section One.
Section One is an ultra-secret member of that country's intelligence community and is charged with numerous duties but chief of them is the removal of enemies of the country that cannot be gotten rid of through legal channels. Wet works if needed. It was described in the narrative as "a black-ops programme that combined civilian intelligence gathering with paramilitary direct action. It allowed small teams of covert operators to find, fix and finish threats anywhere, everywhere". Additionally, "for all intents and purposes, Section One was a revolution. One that hit fast and hard, neutralizing persons of interest, disrupting terror networks. And it laid the groundwork for a new intervention policy – why publicly commit thousands of troops for kinetic action when you can just send in a handful of quiet professionals? Easy in. Easy out. Seamless".
At least it was until an op went very wrong in Kuala Lumpur and a key agent named Nathan Raines died. Then the same politicians who had eagerly created it went about gutting it. Now it is run by Deirdre Raines, former agent herself and widow of the slain agent. She is a woman who holds the appellation of Ice Queen, has earned that nickname many times over, and who would appreciate knowing she owned it but who would have been very unpleasant to the one letting her know.
Kendra is a former member of Section One. She "had spent years on the global circuit. Finding, fixing and finishing threats in souks and madrasas and back alleys. Spilling blood in every jihadi stronghold from Baghdad to Kabul to Islamabad". Then a particularly bad mission in the Iraqi capital had caused her to lose it and she was placed on administrative leave to hopefully find a way to get over the problems that caused her breakdown.
When we first start following her, life is forcing that recovery quite quickly.