"The gods have done everything they can for the mortals, but they aren't satisfied. They want more, they wish to overthrow the gods. They want the power of the gods. They know that they will die, but they don't care. They will kill the demi-gods first, then the goddesses, the the lesser gods. Then finally, Zeus himself.
Zeus knows their plan. He must act fast. He calls together all the gods and demi-gods. They form a plan to destroy the rebellious mortals.