(I listened to this on audiobook rather than reading it so I apologize if I spell any names wrong.)
Katniss is a teenager living in what remains of the United States. After war, disease, starvation, etc., it is decimated and a new country called Panem is formed. There is a Capital district which I believe is near the Rockies and 12 other districts fan out from it. Katniss lives in District 12 or the West Virginia/Appalachian region of the country. The main industry is coal mining and everyone there services that industry & the workers within it.
She lost her father in a coal mining accident several years before and never really got over it. Everything in her life was defined by that accident and it has shaped who she's become. She's 16 and cares for her younger sister and her mother. She hunts, barters, trades, and brings in food to her home.
At the time the novel starts, there is something going on. It's called the Reaping. Let me take a step back here. As part of The Capital rising in dominion over the Districts, they defeated the districts in a war. Each District had to sign something called the Treaty of Treason in which they basically admit they suck and that the Capital has the right to rule them. (OK, I'm blatantly downplaying this a bit but that's the general idea.) As part of that rule, the Capital has determined that each district will send two teenagers (tributes) to the Capital to participate in something called The Hunger Games.
Basically, this is to remind the Districts that the Capital rules all and can dictate the course of their lives forever. They are not in control of their own destinies. The Capital is. The Reaping is the selection process in each of the Districts to provide the tributes for these bloody, violent, cruel games. (Think the Olympics where your only chance to win is to survive & kill everyone around you.) One boy and one girl are chosen. At the time of selection, volunteers may come forward to take the place of someone chosen but they rarely do.
For District 12, the unthinkable happens. Katniss's younger sister, Prim, is chosen. She's 12 and completely unsuited to participating in the Hunger Games. Without thinking, Katniss volunteers to take her sister's place. Along with a townsperson named Peeta, she sets out to the Capital & the arena where she'll meet her destiny.
It's a violent and cruel mindgame that the game makers and the other tributes play with all of the participants. I won't tell you how it ends but I didn't enjoy this at all. I have a difficult time dealing with senseless torture of innocent people. Katniss winds up enmeshed so deeply in the game itself that she's completely at a loss as to who to trust or not. Horrible, horrible book. I'm not going to read the rest of the series.