The novel opens with Katniss wandering through the ashes of her decimated district, District 12. It’s been a month since Katniss was rescued from the Quarter Quell arena after shooting an arrow at the force field, the same time her district was bombed by the Capitol. During that month, Katniss lived safely underground in the highly regimented District 13, where the heart of the revolution resides, powered by President Coin, whom Katniss doesn’t completely trust. Katniss is trying to make sense of this new world amidst a rebellion and is still quite unstable as she recovers from the physical and emotional trauma she underwent in the arena.
Katniss’ coming to District 12 was her own idea. She wanted to see her home and mourn for those who were killed. She feels great guilt for everyone who died. Gale heroically led as many people as he could, including Katniss’ mother and sister, Prim, to the Meadow and into safety. Now, the District 12 refugees have been welcomed into District 13, whose population is waning because of a pox epidemic that killed many of the district’s citizens and left a great number of them infertile. Gale waits for Katniss overhead in a hoverplane. Katniss is still trying to make sense of her feelings for Gale, and it is especially hard now as she worries constantly about Peeta, who was captured by the Capitol, wondering if he is alive or dead.
Along with Katniss, the others rescued from the Quarter Quell arena were Finnick Odair and Beetee, who had been part of the rebel plan organized by Head Gamemaker Plutarch Heavensbee. Now, Katniss is experiencing great pressure from District 13’s leaders to be the Mockingjay, the figurehead for the revolution that her defiance of the Capitol has helped inspire. It’s a role that Katniss isn’t sure she can fill. She wonders if she would do more damage than good.
Eventually, Katniss does agree to be the Mockingjay, but it’s only after she sees Peeta on a televised interview calling for a cease-fire, which makes him a traitor even though Katniss is sure Snow made him say it. Katniss creates a list of demands, all of which she requires in order to be the Mockingjay. On that list is Peeta’s immunity. Katniss learns that clothing designer Cinna, before he was killed, had already designed and created all of her Mockingjay uniforms. Katniss discovers her prep team imprisoned in District 13’s cells deep underground; they’ve been horribly abused and mistreated. She saves them and grows increasingly wary of Coin and the way she runs District 13. Katniss continues to see major parallels between District 13 and the Capitol.
Coin calls an assembly per Katniss’ request, not only to announce Katniss’ acceptance of her Mockingjay role, but also the immunity of Peeta and the other captured tributes should the rebels win. Coin adds, however, that should Katniss deviate from her Mockingjay role, immunity will be revoked and all tributes, including Katniss, will be subject to the laws of District 13.
Katniss’ first propo, short for propaganda spot, is an utter failure. It’s staged and stilted, and Katniss doesn’t even recognize herself. Haymitch, now sober since District 13 doesn’t allow alcohol, laughs at the propo and points out that Katniss is most powerful and moving during genuine scenarios. Coin says to send Katniss, a bodyguard team, and a camera crew to District 8 that day to get some more realistic propos.
Katniss and Haymitch are still angry at each other. They both think the other failed to protect Peeta in the Quarter Quell arena. Upon talking, however, they realize neither one of them could have made any other choice. Now, they will work together to win this war and rescue Peeta.
On her way to District 8, Katniss learns that the rebels have control of every district except for District 2, which has always been favored by the Capitol. The rebel plan was to take over each district, ending with 2, cutting off supplies to the Capitol. If the rebels win, the new government will be a republic.
In District 8, Katniss meets Commander Paylor and visits the wounded in a makeshift hospital. The patients call out to her by name, invigorated by the mere sight of her. They want to touch her and talk to her, and suddenly Katniss realizes that she hasn’t been fighting against the Capitol alone. She also recognizes that she does possess power, the kind of power that Snow is afraid of because it inspires unity and hope. Just as Katniss and her team are leaving District 8, another airstrike arrives, targeting the hospital. Katniss and Gale disobey orders and climb to the rooftop on a nearby building to shoot down the bombers. Once the attack is over, Katniss surveys the destroyed hospital. There are no survivors. She is enraged at this disregard for human life and an attack on the defenseless and weak. She delivers a fiery message to Snow, all of it captured by her fearless camera crew.
Back in 13, Katniss and Finnick watch another interview with Peeta, but this time she can see that he has been tortured and is hurt. Katniss and Finnick pretend they didn’t see the interview, and nobody tells Katniss about Peeta, not even Gale. Katniss eventually gets Gale to confess, but she feels betrayed. Gale and Katniss, growing farther and farther apart, return to District 12 to film more propos. Katniss remembers how she used to be happy there and wonders what her life might have been like had she run away with Gale.
During another live Capitol programming, in which Snow and a very battered and fragile-looking Peeta appear together, Beetee is able to break through the Capitol feed to broadcast clips of the rebel propos. While Command rejoices, Katniss knows that their success means more pain and suffering for Peeta. At the broadcast’s end, Peeta warns Katniss and District 13, saying they’ll be dead by morning. The feed cuts out just as Peeta is hit to the floor, his blood splattering the tile.