The Plot of The First Book-The Hungry Games by Suzanne Colines

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 rich Capitol and twelve surrounding, poorer districts. 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 at random and forced to participate in The Hunger Games, a televised event where the participants, or "tributes", must fight to the death in a dangerous outdoor arena until only one remains. The story follows fatherless 16-year-old Katniss Everdeen, a girl from District 12 who volunteers for the 74th Games in place of her younger sister, Prim. Also participating from District 12 is Peeta Mellark, a boy whom Katniss knows from school and who once saved Katniss's life by giving her bread when her family was starving.
Katniss and Peeta are taken to the Capitol, where they meet the other tributes and are 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 permitted to send gifts to favored tributes during the Games. The Games begin with 11 of the 24 tributes dying in the first day, while Katniss relies on her well-practiced hunting and outdoors skills to survive. As the Games continue, the tribute death toll increases, but both Katniss and Peeta are able to evade death.
Supposedly due to Katniss and Peeta's beloved image to 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 manages to outlast all the other 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. Instead, they both threaten suicide and are subsequently both declared winners.
Though she survives the ordeal in the arena and is treated to a hero's welcome in the Capitol, Katniss is warned that she has now become a political target after having defied her society's authoritarian leaders so publicly. Afterward, Peeta is heartbroken to learn that their relationship was at least partially a calculated ploy to garner sympathy from the audience, although Katniss herself remains unsure of her own feelings.