Charlotte Locke is an analyst with Section 47.
Desmond Percy is an assassin with Section 47.
Locke's job for that organization when we first meet her has her at a desk studying reports from her computer but she will find herself out in the field deeply involved in activities she is not trained for. It is her day-to-day task study intelligence reports for information about the "paramortal" world searching for "terrorists, criminals, and other dangerous magic wielders who wished to wreak chaos and calamity on the unsuspecting mortal world". Yes, you read the words 'magic wielders' correctly.
"Like many other spy organizations, Section 47's main mission was to gather intelligence and then use that information to prevent terror attacks, mass-casualty events, and other serious, life-threatening catastrophes. Only instead of tracking and chasing regular mortal bad guys, Section went after those who used magic and enhanced weapons to commit their crimes. In the unfortunate event that an attack did happen, and some paramortals unleashed their powers to rain down death and destruction, Section then covered up and explained away the magical calamity as best it could before hunting down the perpetrators-and eliminating them."
Locke was an employee of the organization thanks to being a Legacy - her parents and grandparents had been with the department so she had a position offered after college, nepotism being common. But of course family connections alone would not have qualified her since to be with Section 47 required you to be part of the paranormal world they protect. That is, you needed a power. Locke's is synesthesia.
Synesthesia is defined as "an anomalous blending of the senses in which the stimulation of one modality simultaneously produces sensation in a different modality". Yikes! How about: synesthetes hear colors, feel sounds and taste shapes.
Locke has "an unusual form" of synesthesia" in that she "could see typos, mistakes, and errors that people made, whether they had accidentally transposed digits and written down a wrong phone number, knowingly fudged their expense reports, or deliberately committed fraud by submitting false information to a financial institution".
That sounds fairly interesting and quite useful as an analyst but hardly sufficiently intriguing to entice readers to follow her activities unless she had actual adventures which she does not and is thankful for not having. Until, that is, you throw in the fact that this ability lets her read patterns and numbers where others see nothing and that in turn means she can "sense danger" before it manifests itself, which out in the field is great, and she is a "human lie detector". Together those two talents, in the right hands, could be crucial.
And that is where Percy comes in.
He is an assassin, though as Locke lets us know, "we didn't actually call them assassins at Section 47. At least, not to their faces. Not if you wanted to keep breathing. No, my secret government agency referred to those men and women as cleaners, as if that somehow masked their true, deadly purpose. They didn't clean up anything. They just created more bloody messes, in every sense of the word".
He needs help on a mission to track down a very nasty and particularly evasive bio-terrorist and Locke's skills are just what is required to give him an edge. Which is why he looks her up and pulls her unwillingly into his assignment.