Here is the basic premise of The Hunger Games, book one, taken directly from Suzanne Collins' website:
Katniss is a 16-year-old girl living with her mother and younger sister in the poorest district of Panem, the remains of what used be the United States. Long ago the districts waged war on the Capitol and were defeated. As part of the surrender terms, each district agreed to send one boy and one girl to appear in an annual televised event called, "The Hunger Games." The terrain, rules, and level of audience participation may change but one thing is constant: kill or be killed. When her sister is chosen by lottery, Katniss steps up to go in her place.
Make no mistake, these books contain some pretty violent subject matter (although we are more told about the violence rather than experiencing it in graphic detail, for which I'm thankful). The games are by definition kill or be killed. Only one victor can remain standing. But at its core, The Hunger Games is about basic human emotions: survival, love, empathy, greed, and how far one will go to keep themselves and those they love alive. It also has a strong anti-war sentiment and asks some questions we should probably all ask from time to time.
I've read the entire trilogy, but to tell you anything about Catching Fire or Mockingjay would be to share major spoilers about book one, so I won't. This is a series you have to read from the beginning. And if you're anything like me, when you start, you won't want to stop.
Have you read any of The Hunger Games books? What's your impression?