Katherine 'Kit' Scarlett is an agent with British Intelligence.
The time period for her adventures is the 1580's. Queen Elizabeth I is still on the throne halfway into her third decade ruling Britannia. Her health is becoming a matter of some concern and her enemies are eagerly awaiting a chance to pounce. Though she would remain in control for another twenty years, the intrigue and the scheming is rampant.
Running the show for the intelligence gathering to help protect the Throne and its occupant is Sir Francis Walsingham, private secretary to Her Majesty for a decade already and well known to be her principle spymaster. It is he who gathered operatives he knew to be both capable and loyal and then oversaw their training in spycraft.
One of his favorite agents is one very few knew anything about, as he planned. Walsingham trained Kit Scarlett from the time she was a young girl, all with the expectation that as a youthful female and thus largely overlooked when matters of state were concerned, she would be able to infiltrate places his male agents would be banned. "The most secret of intelligencers, Kit. That's what you will be," he told her at one point.
The training, as mentioned, started quite young and Scarlett has known and had considerable affection for the man she considers like her own father, so much so that she is determined to show herself worthy of being one of his operatives. Add to that an unquenchable desire for adventure and excitement and even danger, and it is easy to see why someone so young and eager can also be a bit overzealous and even reckless (though she would be loath to admit that last). Her devotion to Walsingham does have a downside, though as "she would never hear a word said against [him], she couldn't bear it".
Scarlett is described as having short dark auburn hair atop a very pretty face with "large bronze-coloured eyes and the small mouth" - all quite feminine. This does make occasionally trying to impersonate a man while undercover a challenge though she is aided by having a naturally "Husky voice".
An early mission which some, including her boss, would consider less than perfect - and she would take exception to that since she accomplished her goal - results in her being partnered with a fellow agent, Scottish born and bred Iomhar Blackwood. Their initial reaction to each other is less than friendly and their working together will prove to be challenging for them and enjoyable for us.