When Charlotte Gray, Luna Harrison, and Michael Taylor are chosen for a perilous quest, they find themselves thrust into the heart of an ancient and terrifying mystery. Tasked with retrieving a powerful artifact hidden deep within the Vault of Endless Night, the three demigods-each with their own strengths, fears, and secrets-must face a deadly adversary: the Shadow King, a being of unimaginable darkness with the power to consume the world. As they battle relentless monsters, unravel cryptic prophecies, and struggle to keep their sanity in the face of evil, they discover something even more dangerous than the Vault itself: each other. With Luna falling prey to the shadow king's influence, Charlotte's wit and cunning, Michael's strategy, and Luna's healing powers are put to the ultimate test. Forced to work together, they learn that their bond is the only weapon powerful enough to defeat the shadows-but their journey is far from over. In this high-stakes adventure, old friendships will be tested, new ones forged, and the line between light and dark will blur. The Vault may have been conquered, but the true battle is just beginning.

SEQUEL TO THE QUEST OF SHADOWS AND LIGHT! After defeating the Shadow King and escaping the Vault of Endless Night, Charlotte Gray, Luna Harrison, and Michael Taylor thought they were free from the darkness. But their victory was only temporary. The remnants of the Shadow King's power still linger in the world-unseen, but ever-growing. As the forces of darkness slowly rebuild, the demigods begin to see strange, inexplicable disturbances around Camp Half-Blood. Whispers speak of a forgotten god-a being whose name has been erased from history, its power buried deep within the earth. Known only as Nyxar, the ancient god of forgotten dreams and shadows, Nyxar is said to have been imprisoned long ago by the Olympians, bound beneath the earth in a prison that even the gods themselves forgot. But something has stirred Nyxar's essence, and the seals are weakening. When the trio is sent on another quest to stop the rise of this forgotten god, they're confronted with a truth darker than anything they've faced before: the darkness doesn't just threaten the world-it threatens the very fabric of memory. Nyxar is the god of forgotten things, and with his rise, the world's history will begin to unravel, erasing everything that ever was. To stop him, Charlotte, Luna, and Michael must navigate an even more dangerous path, discovering forgotten ruins, meeting gods and monsters from lost myths, and even facing parts of their own pasts that they'd rather forget. But they're not alone this time: Nyxar's reach extends even into their hearts, tempting them with the power of the forgotten-and maybe even offering them the chance to erase the painful memories of their past battles. But at what cost?