Hades is planning to take over the world, to achieve that goal, he sends out deceased Gold Saints to take Athena's head. Seiya and the other Bronze Saints come to help but their help isn't appreciated by the remaining Gold Saints that are still alive.
After the 12 Gold Saints sacrifice their lives to destroy the Wailing Wall, The Bronze Saints enter the deepest realm of the Underworld, Elysion, where they face off aganist Hades's two most powerful servants: The Twin Gods, Hypnos and Thanatos, before they can reach Hades for the final battle.