Katniss is recovering from the previous book's events, where she and Peeta won the Hunger Games. Everything at home in District 12 has changed, including Katniss' relationship with Gale. She and Peeta still have to pretend they're an item, although her feelings for Gale are totally unresolved.
Before Katniss, Peeta, and Haymitch leave town for the Victory Tour they're traditionally obligated to take, President Snow stops by to warn Katniss that he's watching her. He doesn't want to see any more rebellious stunts. Somewhat daunted, Katniss prepares for the tour.
Once they leave, Katniss takes Haymitch aside for a strategy meeting. He drives home the point that her whole life – if she and Peeta want to survive – will involve this made up love affair. She and Peeta must keep up the show of their puppy love.
The tour's first stop is District 11, home of Katniss' friend Rue from the Games. Peeta and Katniss both overstep the traditional formalities and say too much during the ceremonies. Once again, the pair seems to be rebelliously challenging the Capitol. It seems like a riot is on the horizon, and they watch in horror as brutal punishments are doled out.
After that, they move on to the next districts, but are much more careful. By the end of the tour, Peeta has publicly proposed to Katniss. Katniss is still worried that people can tell they're faking it, though. She begins to think of backup plans.
In the meantime, she and Peeta attend a celebration in the Capitol, where she meets the new Head Gamemaker, Plutarch. He shows her his watch, which has a mockingjay on it.
The Victory Tour goes home. Katniss finds out that people in District 8 are verging on rebellion. She realizes that her mockingjay is becoming a symbol of rebellion. President Snow is not going to like this.
Katniss has a lot to process, so she arranges a private meeting with Gale. They talk about running away together, but just end up arguing. Gale wants to rebel and Katniss doesn't. He storms out, and she goes to find Peeta, who says that he'd follow her if she wants to run away. Their conversation is interrupted, though, when they find Gale being whipped in the town square as punishment for hunting game. Katniss gets in the middle of it and is injured. She sees that her friend Darius tried to do the same and is in serious trouble.
Katniss gets Gale home to her mother for healing. He's barely alive, and Katniss is conflicted. She's losing her identity. She still feels caught between Gale and Peeta. Over time, she gathers herself and realizes she has to keep fighting against the Capitol; she's can't just run away. Haymitch advises that she and Peeta continue with their wedding plans.
Another day, Katniss goes into the woods for some peace and quiet, but runs into some strangers who show her a mockingjay sign. Katniss finds out that the two strangers are rebels from District 8 on their way to 13. Katniss thinks that the Capitol destroyed District 13 long ago, but the others say it's been rebuilt. She sends them on their way, but can't shake the info they've given her. She tries to go home from the woods and realizes she's trapped outside by an electric fence. The administration is trying to get her into trouble. She has to think quickly and outwits them, but hurts herself in the process. While she's recovering, she finds out more about District 13.
After several months, another political event looms and Katniss has to pose for wedding pictures. She's been gathering clues that many districts are rebelling and shares it with Haymitch. Before they can do much about it, though, they receive strange news. The next Hunger Games are announced, a special version called the Quarter Quell. The Quells celebrate anniversaries and are extra gnarly versions of regular Games. In this one, the 75th Games, former winners will have to re-enter the arena. This means Katniss has to go back and risk almost certain death for the second time.
Katniss does what any normal person would do: she goes into hysterics. She and Peeta both go to see Haymitch and they all commiserate. Two out of the three of them are going back to the arena. Katniss makes Haymitch promise he'll help her save Peeta's life this time around.
The next day, Peeta turns into a taskmaster and pushes them all to start prepping for the Quarter Quell. They work out to get into shape and strategize as much as they can. Then the Games arrive. Katniss and Peeta are sent off straightaway. Both are glum. They have some time together as they travel to the Capitol for pre-Games events, and they use that time to strategize further. They study previous Games and how other tributes won.
In the Capitol, Katniss' prep team, including her stylist Cinna, pretty her up. She and Peeta head to the opening ceremonies of the Games dressed like smoldering coals. They are a huge hit. They also meet some of their opponents, like the handsome and dangerous Finnick and the off-kilter Johanna.
Then Katniss and Peeta have a bit of time to train for the Games. Haymitch wants them to select allies, but they're not really into it. They evaluate the other players, but Katniss really just wants to be alone with Peeta. On the last day of training, they have to face the Gamemakers alone and show off their skills. Both Katniss and Peeta do foolish and brave things. Peeta paints a picture of Rue after she died in the last Games, while Katniss hangs a stuffed figure and names it after the previous Head Gamemaker. They both score the highest "danger" rating in the evaluation.
Peeta and Katniss get closer and closer. Then it's time for the last public event before the Games: interviews. At the televised interviews, each of the tributes takes a dig at the Capitol when it's his or her turn to talk. Katniss makes quite a sensation with her costume: she's wearing a wedding dress that transforms into a feathery mockingjay outfit. Her designer, Cinna, put himself in great danger by creating it. Then Peeta goes even further by telling the audience that he and Katniss are already married and that Katniss is pregnant. This really pulls the audience's heartstrings and fuels further unrest throughout Panem.
It's not enough to get our favorite "couple" out of the Quarter Quell, though. They have a day or so of relative peace and then have to head to the arena. Haymitch wishes them luck and tells Katniss to remember who their real opponent is. Then Katniss and Peeta separate. Cinna goes with her as she is readied, finally, for the arena. As Katniss is being transported to the Games, she has to watch helplessly as Cinna is viciously beaten. President Snow definitely didn't like the outfit Cinna made for Katniss on interview night.
Katniss is dumped into the arena in an area surrounded by water. When she's free to move she swims desperately to the supply center, racing the other tributes to get her hands on a weapon. Luckily, she finds a bow and arrows waiting for her. She has an encounter with Finnick (from District 4), who's also armed, and the two of them work together to save their friends, Peeta and Mags. The other tributes disperse, and our friends from 12 and 4 head out into the jungle.
The first challenge is finding freshwater, which they have to tap from the trees. Katniss realizes that the whole arena is bound by a force field, info that will come in handy later.
Next up is evading a poison gas. They don't all make it out in time, and Mags sacrifices herself so the other three can continue. They are all affected by the gas and collapse when they get back to what they think is the safety of their original position on the beach. Once there, though, they're attacked by vicious monkeys. Peeta almost dies but another tribute saves him in the nick of time. By the end of the day, many tributes have already died.
The next day, they meet up with three more potential allies: Johanna, Beetee, and Wiress. Wiress and Beetee are in bad shape. Beetee's holding on for dear life to a special weapon, while Wiress just endlessly says "tick, tock." Eventually Katniss realizes that Wiress means that the arena is a clock. (Thank you, Wiress.) The group figures out that the arena has different danger zones that go off on schedule, according to the hour, and are organized in the shape of a clock. Soon after, Wiress is killed by other tributes.
The allies take down some of the enemy tributes, but the rest escape when the entire arena shakes with a mini earthquake. The allies keep moving, making sure to retain Beetee's weapon (a long coil of wire). In one area of the arena, Katniss and Finnick are briefly separated from the others and have the agonizing experience of hearing the voices of the people they love screaming in pain. They make it out, but pretty emotionally traumatized.
Katniss and Peeta fight over which one is going to die to save the other. Meanwhile, the team schemes about how to take out the remaining tributes who aren't their allies. Beetee has a plan to electrocute the arena with his handy coil of wire. The group gets separated while they're putting his into action, and chaos ensues. Katniss is brutally wounded but still realizes a significant part of Beetee's plan. She winds the end of Beetee's wire around one of her arrows and shoots it into the force field. The arena explodes.
Katniss is barely conscious enough to realize that she's been taken out of the arena. When she finally comes to, she's in an aircraft with Plutarch and Haymitch, along with Finnick, Beetee, and some others. She learns that this was part of a master plot, and that there is a serious group of rebels, based out of District 13, working to take down the Capitol. She learns that all of the effort in the Quell was to protect her, because she's the rallying point for the entire rebellion and the face of the revolution.
But Peeta hasn't been saved from the arena. The Capitol got him, which is obviously really, really bad. Katniss plunges into dark despair. The only thing that brings her out is news from Gale, who also happens to be on the aircraft. Gale breaks the news to her, very gently, that their entire home district has been destroyed.