After a doctor joins Gus and his crew, they seek a way to the coast and stumble upon a plane owned by a family in desperate need of medical attention.

After a daring rescue, Gus meets an individual well-versed in hybrid history. Amid emotional reunions and eerie revelations, all roads lead to the cave.

With loved ones beside him, Gus goes on a treacherous journey into the cave to find a cure once and for all. Meanwhile, chaos breaks out at the outpost.