In Catching Fire, Katniss Everdeen, the Girl on Fire, became the Mockingjay, the living breathing symbol of the Rebellion against President Snow and Panem.
In Mockingjay, Katniss, finds out that the more things change, the more things stay the same.
After doing propos for District 13's President Coin and inciting the rest of Panem to rebel, Katniss and Gale and the other victors from the Hunger Games and Quarter Quell are forged into a special unit. They are the best shots in the rebel forces, but they're relegated to being political tools for District 13's President Coin.
After a desperate warning from Peeta about an upcoming attack, Katniss pushes for his rescue. She's left behind as the mission is done and successful. Peeta being brainwashed to kill Katniss on sight dampens any triumphant feelings, though.
After successfully compromising a key Capitol stronghold in District 2, the rebels decide to take the fight to the Capitol. What follows is a harrowing journey to the heart of the Capitol where Katniss' mission is jeopardized by Peeta's presence and the sneaking suspicion that Snow isn't the only one who wants Katniss
The finale to a series carries high expectations to not only measure up the the previous chapters of the saga, but also tie up all the loose ends and answer every question. In Mockingjay, Suzanne Collins does all of that and more and makes it look effortless. There are many surprises and cliffhangers (one of them literal), but in the end it comes down to Katniss, her bow and her courage. Just as it should.