Zeus must free Juno from the underworld or risk losing both Juno and Kali due to their psychic link, but the Underworld has been warded by magic and he cannot enter that realm. Flynn, a mortal, can though, and he suggests that he lead the Zodiac into the underworld to rescue Juno. This is an adventure that will literally bring the Zodiac through hell with Titans, monsters, and Gods like Prometheus. Some of the Zodiac will not return. And ultimately Juno will have to choose between what she knows in her heart to be right and what she wants. Ultimately her psychic link with her twin will save her, her twin, the zodiac, and the world, as they push back the apocalypse.