In this Percy Jackson mini adventure first published in The Demigod Files, the goddess Persephone summons Percy, Thalia, and Nico to the Underworld to retrieve Hades's powerful sword before it falls into the wrong hands. Easier said than done in a realm full of daimons, ghosts, and monsters. Not to mention Iapetos—brother of the powerful Titan lord, Kronos. Will the demigods manage to find and return the sword before it's too late? Includes an excerpt from the upcoming novel The Sun and the Star: A Nico di Angelo Adventure by Rick Riordan and Mark Oshiro.