Mrs. Smith's Spy School For Girls is a training facility on behalf of the Center.
We are told very little about the Center other than it is a government organization, part of the American Intelligence Community, and it's major point of interest is that it "uses kids to ferret out information no one else has any hope of acquiring". As Mrs. Smith tells new student, Abby Hunter, "No one ever suspects a child. Children can go practically anywhere without arousing suspicion. This is the cornerstone of our operation. We train young people to participate in the security of this great country."
"The theory is that kids are invisible (unless they're behaving badly, and then everyone has an opinion) and therefore make really good spies." But the Center does have a restriction that no one under 16 is made operational for the field. That does not mean, of course, that training cannot start a whole lot earlier.
Mrs Smith and her faculty do just that; they search out and vet those youngsters who have shown the most promise for a life in the cloak and dagger world and invite them to attend the school, located in Connecticutt. Of course, many of the prospective attendees are recommended to Mrs. Smith, like Ms. Hunter whose name was placed on the potential list by none other than her own mother. [Mom, you see, slightly scattered brain though she might seem at times to her daughter, is an experienced operative for the Center already.]
Now enough about the school, let's discuss the main student attending it. Okay, main is not the right word because there are a good number of other students. But the main one that we follow is Hunter and let me tell you she was not at all happy about having to go. She is very happy in the school she has been going to for quite some time and has some close friends she has no desire to leave behind. Why did Mom not only go along with the idea but was the one who started the ball rolling? Unfair!
At least until she got there and found out what they were teaching and found out that Mom had been an agent of the Center for years and maybe Abby could be even better than Mom. And being a spy is, well, way cool!