Haymitch had said to remember who her true enemies are. She understands the true enemy is not Finnick or Enobaria but is the Capitol. Grabbing Beetee's knife, she unwraps the wire from it and coils it around her arrow instead. She locates the hole in the force-field that Beetee and Wiress showed her the first day of training and aims the arrow at it as lightning hits the tree.
The force of the arena exploding sends Katniss flying backward. A hovercraft appears and takes her away. She thinks that the Capitol is taking her away to torture and kill her in front of all of Panem to punish her for the rebellions and the explosion of the arena. However, after waking up from a drug-induced coma, Katniss finds Plutarch, Haymitch, and Finnick on the hovercraft discussing strategy. They tell her that she is on her way to District 13, which actually does exist. All three of them, Johanna, Beetee, Wiress, and many of the Quell's other tributes were conspiring together to overthrow the Capitol and rescue Katniss and Peeta from the arena.
When Katniss thought Johanna was stabbing her arm, she was actually cutting the tracker out and luring the careers away from Katniss. Most of Panem is in full-scale rebellion against the Capitol and Snow, and Plutarch says that he showed Katniss his mockingjay watch to gain her trust.
Katniss and Peeta weren't informed of the plan because it was too risky. This upsets Katniss, and she begins to feel betrayed by her friends. She thinks that her allies have been more secretive than her enemies, and she's hurt by Haymitch's lying to her.
Haymitch tells her that while she lives, the rebellion lives. Katniss is the mockingjay, and she herself has given the rebels the inspiration necessary to rise up against Snow and the Capitol. The other tributes were working to save Peeta because they knew without him, Katniss wouldn't want to fight.
However, nothing can prepare her for when she finds out that Peeta has been captured by the Capitol. She attacks Haymitch and loses the will to live. She stops eating and speaking. The only one who can pull her out of her depression is Gale, who tells her District 12 has been bombed and no longer exists.