Kim Maxwell is an agent with British Intelligence.
With these activities taking place during World War II, the section of the intelligence community she is deeply involved in is the Special Operations Executive (SOE) under the direct leadership of Brigadier Colin Gubbins, known to all in the SOE as 'M'.
When we meet her initially and briefly, she is the subject of a coded radio transmission from Occupied France back to SOE Hq requesting an immediate evacuation flight; the identity of the person being brought back to London is Maxwell and though we are told very little at the time, she is in a very bad way having 'enjoyed' the company of the Gestapo and just barely surviving it. When the tale jumps ahead several months later, in 1943, she is described as 'robust' and chafing at being placed for recuperative purposes in a job doing 'menial routine work'. She wants immensely to return to the field where she has proven to be more than qualified.
Her full name is Katherine Maxwell though her friends call her Kim and in the SOE she is more often addressed as Max. She holds the rank of Lieutenant in the First Aid Nursing Yeomanry but that is more for administrative and secrecy purposes. She is described as "a slight figure, no more than five feet four inches tall" but her boss was well aware that "the slender form was "capable of feats of strength and endurance that would put many male athletes to shame". "Her face, framed by unfashionably short dark hair, was elfin, with its pointed chin and high cheekbones, and dominated by a pair of grey-green eyes that could sparkle with amusement but which could also sustain a calm, assessing gaze that many people found disconcerting."
To the casual viewer, Maxwell's wounds from her time in captivity shows "only a faint scar running from the corner of the right eyebrow to her lip" but beneath her uniform her injuries were far worse. Her determination to be of service in the espionage portion of the war effort, though, is stronger than ever.