Perseus, a son of Zeus, lives as a fisherman after the death of his wife, Io, with his young son, Heleus. Zeus visits Perseus and asks for his help, saying that humans are not praying to the gods and as a result the gods are losing their power and becoming mortal. They can no longer sustain the walls of Tartarus which are crumbling, and the imprisoned Titan Cronus will soon be free. Perseus, valuing his family's safety, refuses to get involved.