As Xena prepares to give birth, Hercules arrives to protect her and her unborn child from Zeus in an emotionally charged and highly anticipated episode. Zeus learns from the Fates that Xena's baby, who was "not begotten by man," will bring about the twilight of the gods, and he orders her death. When Hercules finds out, he vows to protect her at all costs. Knowing the gravity of the inevitable confrontation, Xena and Gabrielle descend into Tartarus to find Hades' helmet of invisibility, while Hercules searches for a dagger made from the rib of Chronos-the only weapon that can kill his father.