Ten years have passed since District 13's failed rebellion by against the authoritarian structures of the Capitol, and the country of Panem is still reeling from the aftermath of its long and bloody civil war. Although the Capitol won, they know that their victory is by no means assured permanently. A horrifying competition called the Hunger Games has been put in place to remind the Districts about the consequences of dissent: every year, each of the 12 Districts is forced to send a randomly selected male and female child to fight in a televised death match, with only one survivor. Although a decade has passed, hatred between the Capitol and the Districts remains strongly entrenched. The Districts resent the Capitol's authoritarian control over all aspects of their lives, and the citizens of the Capitol resent the people of the Districts for the destruction of their homes and for the many tragedies of the war. In the Capitol, where wealth and class are the most important aspects of belonging, lots of formerly affluent families are forced to maintain a facade of prosperity while secretly starving underneath. 

We meet 18-year-old Coriolanus Snow, a member of one of these once-prominent dynasties now struggling to maintain the appearance of wealth. Living with his grandmother “The Grandma’am” and his cousin Tigris in a decaying, once-grand apartment, Coriolanus will stop at nothing to change his circumstances. He’s a brilliant student, conventionally handsome, and a clever people-pleaser. He knows that success at school and later at the University will guarantee him the contacts and training he needs to fulfill his rightful place as one of the leaders of Panem society. However, he needs funds to get there, and the only way to get them is by winning one of the Academy's prizes so that he can afford higher education. In order to achieve this goal, he volunteers as a mentor in the Tenth Hunger Games, hoping to impress the right people and secure what he believes is his rightful future. He worries about his ability to do so because Dean Highbottom, the head of the Academy, appears to have it out for him for reasons Coriolanus can't explain.  

Assigned to mentor a fragile-looking girl named Lucy Gray Baird from District 12, Coriolanus is initially extremely disappointed: he doesn’t think she’ll survive the first day of Arena battle. However, his concerns are quickly assuaged when Lucy Gray Baird proves to be a star in the making. She's beautiful, flamboyant, and fascinating, more so than anyone else Coriolanus has ever met—apart from possibly himself. Lucy excels at manipulating people in order to get what she wants. She weaponizes her musical talent and charm, captivating the audience at her Reaping and calling attention to herself as a tribute to watch. Far from his first impressions, Coriolanus finds himself so happy with her that he refuses to swap her for his friend Sejanus Plinth’s strong, promising tribute, Marcus. Sejanus and Marcus were born in the same District and went to school together when they were younger, and Sejanus struggles with survivor’s guilt for having escaped the Reapings, and for his life of comfort and ease in the city. 

As the Games approach, District 10’s female tribute Brandy publicly murders her mentor Arachne Crane and is shot to death in a zoo cage. This sparks a crisis of confidence in the Gamemakers, who act quickly to smooth things over. The mentors, including Coriolanus, are forced to take the tributes on a televised tour of the arena. However, tragedy strikes as bombs are detonated all around them. This act of terrorism leads to several deaths and injuries, tribute and mentor alike, and to Marcus’s escape. 

Lucy saves Coriolanus’s life: in return, she asks that he take her seriously as a potential winner. He starts strategizing with her, and the two begin to fall in love. The games begin, but instead of the conventional opening sequence, the Gamemakers show the beaten and tortured body of Marcus suspended from a framework over the arena gates. The audience is horrified, especially Sejanus. Sejanus disappears, but his mother, Mrs. Plinth, spots him on a television screen, walking around inside the arena. Dr. Gaul and Dean Highbottom assign Coriolanus to sneak into the arena and get Sejanus out without anybody noticing they're there. Sejanus threatens to kill himself on live TV as a way to protest the Games, but Coriolanus convinces him this isn't the right thing to do. 

As the Games continue, Coriolanus is worried that Lucy will not be able to survive the brutal way the arena pits tributes against one another. Later during the Games, Dr. Gaul’s team releases genetically modified snakes trained to attack those with unfamiliar scents. Coriolanus, who happened to encounter them previously, uses Lucy's handkerchief to familiarize the snakes with her scent. This, along with Lucy’s own familiarity with reptiles saves her from their bites. Conditions in the arena, including the snakes, the cold, rabies, and attacks from other tributes thin the herd, until Lucy is the only one left. She and Coriolanus win the Games, the first mentor-tribute pair to do so. Coriolanus is exultant, but his cheating to help Lucy almost immediately comes to light. Faced with disgrace or joining the Panem militia and becoming a Peacekeeper, he chooses the latter. He asks to be assigned to District 12, where Lucy lives. There, he reunites with Sejanus and rekindles his relationship with Lucy. 

Sejanus's increasing involvement with rebel forces and discontent with the Capitol worries Coriolanus, who eventually records his friend’s confession to helping the rebels and attempting to free a prisoner using a genetically modified bird called a jabberjay. Although Coriolanus doesn’t consciously decide to turn him in, Sejanus is arrested and executed. Coriolanus is left in a tangle of incriminating evidence for two other murders that happen around Sejanus’s escape attempt. Lucy is also implicated, and they decide to run away together. 

However, the romantic escape doesn’t go as planned. Coriolanus doesn’t want a lonely life in the chaotic wilderness. Choosing between his love for Lucy and his ambition, Coriolanus opts for self-preservation. He destroys the murder weapon, allows Lucy to run from him—and presumably escape Panem alone—and leaves District 12 for officer training. However, his destination is not District 2 as expected but the Capitol, where he learns that Dr. Gaul has been orchestrating his life all along, weaving her threads through every decision he has made. He gratefully returns to the Capitol as her protégé. 

In the epilogue, Coriolanus, now known as simply “Snow,” has found his way back into a comfortable seat in Panem’s halls of power. He’s rich again, he’s working on developing new heights of horror for the Hunger Games, and he’s embraced by the elite who he once feared would reject him. His transformation from an ambitious student to the ruthless President Snow is, at this point, almost complete. Coriolanus is gone, and Snow is a colder and more deadly man. He’s determined to crush chaos and rebellion in all its forms, and to never let his emotions overrule his ambition again.