Fear. 

Pete experiments with his new state of existence by tampering with the inhabitants of the FAYZ, resulting in gruesome deaths as he clumsily changes their DNA. The energy barrier begins to turn black, gradually filling the Zone with darkness. On the outside of the barrier, Connie Temple (Sam and Caine's mother) learns that a small part of the army plans to nuke the barrier. Through mental communication with Pete, Astrid learns that the barrier is connected to the gaiaphage. Drake captures the pregnant Diana and brings her to the mine shaft. Diana gives birth to her baby, whom the gaiaphage then inhabits. Drake, Diana, Penny and the gaiaphage, now known as Gaia, head to the energy barrier, where they encounter Sam and Caine. The gaiaphage plans to open up the barrier. They battle, and Sam attacks Gaia; sunlight instantly returns to the FAYZ as the energy barrier becomes transparent. Sam once again attacks Gaia, who is seemingly unhurt. She flees the scene along with Diana and Drake. Visual communication begins between the inhabitants of the Zone and the outside world.