In the first third of the book, we are introduced to our protagonist, Katniss Everdeen. Though she's only a teenager, she's a tough hunter who puts food on her family's table. Her father is dead and she lives with her mother and sister Prim in District 12 in the country of Panem. She hunts with a guy named Gale who is cute and might even have a thing for her, but who knows? Katniss is not very in touch with her mushy side.
Every year the Capitol of Panem hosts an event called the Hunger Games where two "tributes" – a boy and a girl – are drafted from each of the twelve districts to be brought to an arena and fight to the death. (BTW, back in the day the word "tribute" referred to a payment to a ruler.) Only one person can win. This is to remind the country not to rebel – and for entertainment, of course. This year, unfortunately, Katniss's little sister is selected for the Hunger Games, so Katniss volunteers to take her place. Also selected is Peeta Mellark, the baker's son, who maybe has a teensy tiny crush on Katniss. Maybe.
After the reaping (that's the tribute selection process), Katniss and Peeta are whisked away to the Capitol to prepare for the Games (and primped for live TV). We meet their support team, which is primarily comprised of Haymitch (a former Hunger Games winner and also a drunk), Effie (their wrangler), and Cinna and Portia (their stylists).
During the opening ceremonies, Cinna and Portia dress Katniss and Peeta in flames and they draw much attention to themselves. During training, Katniss reveals her archery skills to the Gamemakers and scores an amazing 11 out of 12. Peeta gets a lower score and asks to be coached separately. Peeta also announces in an interview that he has a mega crush on Katniss. Is this all just a strategy to gain audience support and sponsors? Katniss thinks so, but it works well for her too, so she plays along.
At last: Let the Games begin!
All 24 of the tributes are transported to the arena to fight it out. Katniss is on her own at first, but then she discovers that Peeta has teamed up with the Career Tributes – the strong kids from the rich districts in Panem who actually want to go to the Hunger Games. They eventually corner her in a tree, but she drops a tracker jacker nest on them (that's like a genetically mutated killer wasp) and scores a bow and arrow in the process.
After this, Katniss teams up with Rue, a tiny girl from District 11 who reminds her of her sister Prim. The two are able to take out the Career Tributes' food supply, which totally infuriates their leader, Cato. Also, Peeta doesn't appear to be teamed up with them anymore. Where is he? Wounded? Unfortunately, Rue is killed around this time by one of the Career Tributes. Katniss honors her body by covering it in flowers.
After Rue's death, the announcer, wanting to bring back the romance story between Peeta and Katniss, changes the rules of the game: two people from a single district can now win. Before she can stop herself, Katniss calls out Peeta's name.
Katniss goes hunting for Peeta and eventually finds him. He is wounded and camouflaged in the muddy bank of a stream. She nurses him back to health and realizes that by playing up the romance angle, they can get gifts from sponsors.
Eventually, Katniss and Peeta must face off with Cato, the only other surviving tribute, but before that they are all pursued by wild dogs which are actually genetically mutated killing machines. Finally, Katniss shoots Cato and he falls into the pack. They've won, right? Wrong. An announcer comes back on and says the rules have changed back: only one winner allowed.
Katniss and Peeta can't kill each other, so they make a show of taking poisonous berries in an act of double suicide. Fortunately, the announcer comes back on before they can kill themselves, and says that they win. Woo-hoo! They defeated the Hunger Games! Or wait…did they?
Katniss and Peeta keep up the star-crossed lovers routine for the post-games reunion and interview, knowing that this is the only way to keep from being punished by the Capitol for the rebellious trick with the poisonous berries. Eventually Katniss figures out that Peeta really is in love with her – he wasn't acting at all – and he figures out that she wasn't ever in love with him. Oops. As the train pulls into District 12, they put on a happy face for the camera, take each other's hands and step onto the platform.