Katniss returns to the ashes of District 12 to look around. Noticing that the victor's village is still in tact, she goes to her old house. She grabs her father's hunting jacket, the book of plants, and Prim's cat Buttercup. They head back and Katniss goes about her life in District 13 trying to deal with all that has happened. She gets a schedule printed on her arm daily that she mostly ignores. She sometimes sees Finnick, who has gone somewhat crazy. Mostly, she is with Gale and her family. However, she is starting to wonder if the rebels are really any better than the Capital.
With a few conditions (immunity for the other tributes, Buttercup, hunting), Katniss agrees to be the mockingjay for the rebels. They try to film some propaganda to sneak into the Capital's broadcasts throughout the country, but her performance is flat. Haymitch comes up with the idea of sending her to District 8 to meet the people. While they are there, the Capital sends in hover crafts to drop bombs. Katniss' team worries about getting her to safety, but she ends up running off with Gale following her. They shoot the specialized arrows that Beetee gave them at the planes and Katniss takes one down. They bring the camera up to her and she gives her message to President Snow. They edit this all together and are excited with the results. However, after it airs, there is a message from Peeta to Katniss about finding out who she is really working for. Finnick tells her to pretend like they didn't see it at all. No one brings it up. This starts an argument between Katniss and Gale.
Katniss returns to District 12 so that they can film more propaganda. She sings a song about lovers meeting at a hanging tree to die together. She is reminded of wanting to kill Peeta. They ask them some questions and Gale ends up showing his scars from the whipping. Katniss goes to her old house and packs some things. Gale appears and tells her that he remembers when she kissed him while he was recovering. She kisses him and he points out that she only pays attention to him when he is in pain.
They return to District 13 and the next day there is a meeting. They find that the Capital has put together another live interview of Peeta to try to dishearten Katniss and the other rebels. However, Beetee breaks through the signal and is able to insert small clips into the news cast. Peeta is able to give a cryptic message to District 13: "dead by morning." The last thing they see on the screen is the splatter of Peeta's blood.
District 13 goes into emergency mode further underground into a bunker. Katniss is given the packs for her families supplies. Soon she realizes that Prim has gone back for the cat, Buttercup. She has to stop them from shutting the doors with Prim outside. Prim finally makes it and the doors are sealed. Gale had grabbed the hunting gear, thinking that they wouldn't make it through whatever the Capital has planned. Later that night, Katniss finds Finnick and he tells her that he knows that she loves Peeta, though he initially thought it was just a strategy for the games.
After a day or so, they return to their regular living quarters, which have been destroyed. On the surface, the area that was bomb has two dozen roses from President Snow to Katniss. They try to get her to say a few words for the other rebels, but she breaks down because she knows that anything she says will be used against Peeta. There is a squad a volunteers (including Gale) that are sent out on a rescue mission. Katniss (talking about Peeta) and Finnick (talking about the secrets he has gathered over the years) go live to make some time for the rescue team. They got everyone out except one the Inubaria, who they doubt was being held against her will anyway. Katniss runs to greet Peeta and he strangles her. As it turns out, Peeta was "high-jacked," conditioned with trackerjacker venom to be violent towards Katniss.
Katniss asks to be relocated away from District 13 and is sent to District 2. There is a team of rebels that are working on taking over the district, but this is proving difficult as the Capital’s forces are held up inside a mountain. Gale and some other people from District 13 come to help out. He comes up with the idea of creating an avalanche to trap the people inside. This is done and Katniss is expected to make a speech on the event. However, just as she is on the justice building’s steps, a train comes out of the mountain and people start firing. She tries to talk them into joining her cause, but is shot in the chest.
The next thing she knows, Katniss is waking up in the infirmary of District 13 in the same room as Joanna. They wallow in their misery for a while, with Joanna occasionally stealing Katniss’ morphling medication. They eventually find out that the rebels will soon be attacking the Capital now that all of the Districts are united. Katniss goes to talk to President Coin about going with the troops, but she has been blowing off training and is not a soldier. She promises to start training and President Coin promises to consider. Katniss starts out with some trouble because of her bruised ribs (from the gunshot). The trainer sends her to be healed and she improves, helping Joanna along the way. At the end, they are tested in a scenario where they must overcome what the trainers think are their greatest weakness. Katniss, over comes her inability to follow orders, but Joanna isn’t able to get over her new fear of water that the Capital gave her. Katniss is assigned to Squad 451, the star squad, which includes Boggs (leader), Gale, Finnick, and others who qualify as sharp shooters. They are accompanied by a camera crew.
The star squad is positioned as far away from danger as they can be while still able to get decent shots for the propaganda films. However, there are pods placed throughout the Capital that need to be set off. As they get closer to President Snow’s mansion, Katniss starts making her plans to steal the hollow (electric device with city’s skematics and pod placements). Gale realizes this and lets her know that he is going with her. As a replacement for some of their lost soldiers, President Coin sends Peeta, who is still not completely stable. Katniss realizes that the Coin is trying to have her killed. Boggs points out that it is probably because she doesn’t want to lose her position of power and Katniss isn’t exactly backing her. The entire squad starts helping Peeta by telling him what is true and what was falsely implanted by the Capital.
On the next pod that needs to be set off, the camera crew films the entire thing. They go back for reaction shots, but there is a mine that Boggs finds and it blows his legs off. They get into a house as a thick, black for starts filling the streets, setting off random pods. Before Boggs dies, he transfers the hollow to Katniss. He tells her not to go back, don’t trust them, and to kill Peeta. Katniss is unsure of what to do, so she decides to listen to him with the exception of killing Peeta. She leads the group out of the house and into another one farther away. As they rest up, Katniss tells the group that she is on a special mission. They can either go back or follow her. They all decide to follow. There is an emergency newscast on the TV that pronounces their entire squad dead, the first house they were held up in is burning to the ground. They take the opportunity to start moving and decide to go underground.
Luckily, one of their camera crew, Pollox (an avox that used to work in the underground system) knows where he is going. They start making their way to Snow’s house, but when the Capital finds out that they aren’t really dead, they release mutts into the sewers. They end up losing more of their team, including Finnick between the pods and the mutts. They eventually make it into a fur shop run by a woman named Tigress. Eventually, they are able to disguise themselves and walk among the other refugees on the streets. Katniss and Gale stick together and make their way to the front of the President’s house. It is surrounded by children, forming a human wall for protection. A hover craft flies above dropping silver parachutes. The children, associating them with presents, grab for them and they explode. Rebel medics, including Prim, rush in to help. The second set of parachutes goes off and the most of the people are killed. Katniss watches her sister blown up and passes out.
Katniss wakes up in the Capital, her skin being restored from the burns. She is trying to deal with everything that happened when she finds out that she will be the one to kill President Snow. She goes to the garden to find a rose for Snow to wear during his execution. She finds that Snow is being held captive there and he tells her that the rebels are the ones that dropped the bombs. She realizes that there might be truth to this considering that the Capital didn’t have any hover crafts available. President Coin leaves it up to the remaining victors to decide whether the Capitals children (mostly of the higher ranking officials) should participate in the last Hunger Games. The vote comes down to Haymitch, who sides with Katniss. There will be one more Hunger Game.
They prepare Katniss and bring her out to shoot him from a distance of about ten feet. She aims the arrow, but shoots President Coin instead. She stays in the same room that she stayed in before each of the Hunger Games and waits while her trial happens. It is determined that she will return to District 12 and continue to talk to her shrink by phone. Gale takes an important job in another district. Peeta eventually returns to District 12. Katniss realizes that she loves him and they stay together, keeping each other from going crazy. Eventually, they have two children, who she worries about learning the truth about their involvement in the Hunger Games and the rebellion.