Harper Chandler is an agent with DPS.
That acronym stands for the rather oddly named Dogwood Protection Services. It is an interesting name for a company that does the sort of things that DPS does but it seems quite perfect for the kind of work they prefer the general populace to think they do.
In the case of Chandler who at 16 might seem young for the employment she has, the DPS name works out well with her friends and family who think she is a clerk with the organization and that it offers private security to businesses and wealthy individuals. In fact, its main purpose is to "keep the terrorist attacks under wraps". As Chandler explains, "I hate lying to my parents but there's no way they'd let me board the vigilante train". Still, "at the end of the day, it doesn't matter. I help pay the bills".
This all takes place over one hundred years in the future when "after the war of 2098, the United States is a chaotic mess". We are not given a lot of information about the upcoming war except that it seemed unexpected and turned out to be devastating. Much of the East Coast has been obliterated with DC the first to go. The capital of what remains of the nation is in Las Vegas which had worked especially hard to rebuild itself after just about everywhere had been knocked down a peg or two with the explosion of a massive electromagnetic pulse weapon. Some time has since passed.
We are told that the new world has some unpleasant aspects to it in that while during the day the city in which she lives "is like Pleasantville during the day and Gotham at night". Going out after dark is something that Chandler actually prefers ("way more interesting") but a whole lot more dangerous. Case in point: riding the commuter rails late at night seems a good way to not get to where you want.
Chandler keeps her employment with DPS a secret from everyone, including her parents. She took the job because her family desperately needs the added income. Her father's income has dropped significantly as work opportunities disappear and her mother's medical bills have been especially onerous. This makes for an interesting situation in that Chandler works for DPS, doing the often very dangerous assignments her boss, Rigg, hands her, because she is financially strapped. In truth, though, she enjoys it so much that were situations different, she might have done it for free.