Delta Mission is an agent with the NSIB.
That stands for the National Security Investigative Bureau.
We don't ever learn too much about this NSIB other than it is pretty big and powerful and obviously has a whole lot to do with national security, both foreign and domestic. Other than that, well, not so much but as things go, it is not that important for us to know about it other than it exists, she was one of is star operatives until a hit was put out on her, and now she is in hiding until ... who knows!
If this sounds a wee bit familiar, you might be thinking about her first cousin once removed, , a fellow former NSIB operative whose adventures we have been following in this compendium and who also had to go into hiding but for a different reason.
Delta's cover is a sweet one, literally. For reasons I did not quite get if they were actually given, it was decided that she would be handed a food truck devoted to selling ice cream and she would become nomadic with it, traveling from town to town around the country so as to make it harder to find her. Delta is hiding out from a Middle Eastern arms dealer who would love to get his hands on her, both figuratively and literally, the last one guaranteed to not be in her best health. The idea was that if she kept in motion, tracking her down would be a much more complicated matter.
Although if it was learned that she drove a food truck, finding the brightly painted vehicle with the large cone on top of it and the big letters announcing "I Scream for Ice Cream" might not be quite so tricky.
Going by the name of April Waters now, Delta is described by her cousin Charlotte as "pretty, funny, smart, outgoing, and she was a fantastic spy. She managed to enamor people to her and maintain her cover by being that 'girl next door' who's a little quirky, but also kind". When we first meet her she wears her short auburn hair in a "pixie cut that made her look waifish and cute". Being cute looking is a great cover as it makes her opponents undervalue her danger and more than one have learned to regret it.