After dinner, Beetee and Finnick wrap the wire around the tree. Katniss and Johanna are to travel back down through the jungle and to the water, unwinding the wire as they go. Peeta is to stay back with Finnick and Beetee.
Katniss and Johanna move quickly through the jungle, stopping only when the wire is cut from above them. The next thing Katniss knows, she's hit in the head with the metal cylinder of the wire, and is lying on her back. Johanna is kneeling on top of her, stabbing her forearm and digging into it.
Johanna tells her to stay down and she runs away. Katniss is still mulling over Johanna's command when she hears Brutus and Enobaria walking toward her. The two Careers leave her alone, though, saying she is as good as dead.
As she drifts in and out of consciousness, Katniss realizes the alliance is over and that Johanna purposefully knocked her out and cut her arm. She stands up and tries to walk when she fears that Finnick is probably killing Peeta back at the lightning tree.
Though she is vomiting, dizzy, and disoriented, Katniss climbs back up the jungle toward the lightning tree, where she hopes to find Peeta alive. When she reaches the tree, she finds an unconscious Beetee lying on the ground. She sees he is holding a knife wrapped in the wire, and the wire is attached to the lightning tree. She deduces that Beetee must have been trying to drive the knife through the force field, but is still deciding what to do next when she hears Peeta's voice calling out for her.
In order to distract the others from Peeta, she screams out his name. Finnick and Enobaria arrive at the tree, though they can't see Katniss because she is sitting up higher on the slope, concealed by the jungle and darkness. She decides to take the two of them out with her arrows, but then remembers Haymitch's words before she left for the Games.
Haymitch had told her to remember who the enemy is, and she soon realizes who the true enemy is. It isn't Enobaria, Finnick, or Johanna. Instead, it is the Capitol, who created these Games. She takes Beetee's knife, wrapping the wire around the tip of one of her arrows. She releases the arrow at the spot in the force field that Beetee and Wiress had showed her back on that first day of training as the chink in the force field, a hole. The arrow vanishes in the force field, taking the wire with it as lightning strikes the tree and lights up the wire.
She is thrown backward from the impact and is paralyzed as she lies on the ground while the explosions begin.
Beetee's wire and the lightning tree now embody the spirit of rebellion that the people of Panem have felt for so long. The force field reemerges as another symbol of uprising, of using the Capitol's device as a weapon to bring down Snow. The way these three things connect, in a fiery explosion that destroys everything around Katniss, hints at the state of things in Panem. The devices that were once used to manipulate or control the people, such as the Games and the force fields, are now being used to make a stand against the Capitol. Katniss' arrow through the "chink in the armor" will be the final spark that will cause a full scale rebellion to erupt.
Katniss realizes who her true enemies are. She learns that all along, her true enemies, the people she has never been able to trust, are those in the Capitol, the Gamemakers, and President Snow. The Games, the bleak life of the people in the districts, her damaged relationships and stolen future — those are all a result of the Capitol. Everything, including Rue's, Cinna's, Mags', and Wiress' deaths,is because of the Capitol. In this chapter, everything clicks for Katniss.
Though she doubted Johanna and Finnick throughout the novel, her realization of who her real opponents are and the connection of the force field and Beetee's wire are enough to wipe out any suspicions she once had about them or anyone else. She sees the whole picture and understands that they were all working together, though they could never openly acknowledge it.
She understands that her trust was rooted in those who worked to defy Snow and make a stand against his sadistic and cruel Games. Her true allies were right next to her all along, and her ability to completely trust them, the rebels, and her other relationships give her the strength to stand up and shoot the arrow, despite the sickly feeling that fights to overcome her.