The Chalice of the Gods

Percy Jackson is informed by his father Poseidon that, because he was never supposed to exist due to the pact after World War II about the Big Three having no more children, Percy is ineligible for New Rome University. However, Zeus has agreed to allow Percy to attend on the condition that he complete three new quests for the gods and get letters of recommendation from each god. Poseidon helps Percy to put an ad out for his services while assigning a nereid to be Percy's school guidance counselor as further assistance. Percy's girlfriend Annabeth Chase and his best friend Grover Underwood volunteer to help Percy complete the quests.

Zeus' cup-bearer Ganymede responds to the ad, needing help because his chalice of immortality has been stolen and Ganymede needs to recover it before the other gods find out. Percy and his friends investigate Hebe and Iris as potential suspects, and are forced to work around Percy's school schedule. Although both are cleared of any wrongdoing, in exchange for the three cleansing her magical staff, Iris uncovers the true culprit as Geras, the god of old age, and helps Percy, Annabeth and Grover to locate him. Percy challenges Geras to a wrestling match to the death, but ultimately wins by embracing Geras and in effect, old age and everything that comes with mortality, winning Geras' respect and the return of the chalice.

However, Percy, Annabeth and Grover get a distress call from Ganymede that Zeus is holding a sudden brunch for his mother Rhea, meaning that Ganymede needs the chalice back immediately. With the assistance of Grover, Annabeth's cap of invisibility, and Zeus' kitchen staff, Percy sneaks into Zeus's palace where he gets Ganymede alone with the unexpected help of Athena and returns the chalice to him just in time. Ganymede gives Percy a magical piece of paper on which Percy, his pregnant mother Sally, his stepfather Paul and Annabeth dictate his first recommendation letter. Poseidon reassures Percy that he's always watching over him and tells Percy that his small act of heroism in helping Ganymede proves Percy to be a true hero more than any of his world-saving quests did as Percy had kept his promise to the god and challenged Geras not to save the world or to get the letter in the end, but because it's who he is. Percy and Annabeth make plans for their future together and to get the rest of the letters that Percy will need to secure his entrance into college.

The Chalice of the Gods was announced on October 18, 2022.[1] On February 24, 2023, the cover art was announced alongside the final release date for the project. The cover art was done by Victo Ngai, and the release date was September 26, 2023.[2][3]