The Sun and the Star

The Sun and the Star is a children's fantasy novel by Rick Riordan and Mark Oshiro, published in 2023 and set in the world of Percy Jackson, drawing on Greek and Roman mythology.

Nico di Angelo is the son of Hades, and his life has been a sequence of losses: his mother and his sister died early, he was outed against his will, and his friend Jason died during the trials of Apollo. What he has now is Will Solace, son of Apollo and a source of literal sunlight, and the two of them have managed whatever the stories have thrown at them so far. Then Nico starts being plagued by a voice calling from Tartarus, the deepest part of the Underworld. He believes he knows who is speaking: Bob, a reformed Titan whom Percy and Annabeth had to leave behind when they escaped. Nico's dreams and a prophecy convince him that Bob is in serious trouble and that going back down after him is the only option.

Riordan writes myth-based adventure for younger readers, and this book gives two of his supporting characters a quest of their own, with the Underworld standing in for the hardest thing a person can be asked to revisit.