The Hunger Games takes place in an unidentified future time period after the destruction of North America, in a nation known as Panem. Panem consists of a wealthy Capitol and twelve surrounding, poorer districts. District 12, where the book begins, is located in the coal-rich region that was formerly Appalachia.
As punishment for a previous rebellion against the Capitol, every year, one boy and one girl between the ages of 12 and 18 from each district are selected by lottery and forced to participate in the Hunger Games, a televised event in which the participants, or "tributes," must fight to the death in a dangerous, outdoor arena, controlled by the Capitol, until only one remains. The story follows 16-year-old Katniss Everdeen, a girl from District 12, who volunteers for the 74th Games in place of her younger sister, Primrose. Also participating from District 12 is Peeta Mellark, a baker's son whom Katniss knows from school and who once gave her bread when her family was starving.
Katniss and Peeta are taken to the Capitol, where their mentor, Haymitch Abernathy, a former Hunger Games victor, instructs them to learn about the other tributes. They are then publicly displayed to the Capitol audience. During this time, Peeta reveals on-air his long-time unrequited love for Katniss. Katniss believes this to be a ploy to gain audience support for the Games, which can be crucial for survival, as audience members are encouraged to send gifts like food, medicine, and tools to favored tributes during the Games. The Games begin with eleven of the 24 tributes dying in the first day, while Katniss relies on her well-practiced hunting and outdoor skills to survive. As the games continue, the tribute death toll increases. Days later, Katniss develops a short alliance with a twelve year-old girl from District 11, Rue, who reminds Katniss of her sister Prim. When Rue is killed by another tribute, Katniss shoots him through the side of the neck with one of her arrows and comforts dying Rue. She sings to her, and then spreads flowers all over her body as a sign of disgust towards the Capitol.
Supposedly due to Katniss and Peeta's beloved image in the minds of the audience as "star-crossed lovers," a rule change is announced midway through the games, stating that two tributes from the same district can win the Hunger Games as a pair. Upon hearing this, Katniss searches for Peeta and finds him wounded. She nurses him back to health and acts the part of a young girl falling in love to gain more favor with the audience and, consequently, gifts from her sponsors. When the couple are finally the last two tributes, the Gamemakers suddenly reverse the rule change and try to force them into a dramatic finale, where one must kill the other to win. Katniss, in the hopes that the Gamemakers would rather have two victors than none, retrieves the poison berries called "nightlock" from her pouch and offers some to Peeta. Upon realising that Katniss and Peeta mean to commit suicide, the Gamemakers announce that both will be the victors of the 74th Hunger Games.
Though she survives the ordeal in the arena and is treated to a hero's welcome in the Capitol, Katniss is warned by Haymitch that she has now become a political target after defying her society's authoritarian leaders so publicly. Afterwards, Peeta is heartbroken to learn that their relationship was at least partially a calculated ploy to earn sympathy from the audience, although Katniss remains unsure of her own feelings.
source: Hunger games - wikipedia