The Sun and the Star: A Nico di Angelo Adventure is a 2023 standalone middle grade fantasy novel coauthored by Rick Riordan (he/him) and Mark Oshiro (they/them). It is the 17th novel in Riordan’s Camp Half-Blood Chronicles. In addition to Riordan’s 16 Camp Half-Blood Chronicles installments, he has written two other series of mythology-inspired books, The Kane Chronicles and Magnus Chase and the Gods of Asgard. Riordan has also written short stories and supplemental worldbuilding materials for these universes. Oshiro is the award-winning author of a number of contemporary young adult and middle grade books that deal with social justice issues, such as the bestselling novel Anger is a Gift.

The Sun and the Star follows Nico di Angelo, son of Hades, and his boyfriend Will Solace, son of Apollo, as they journey through the Underworld to rescue Bob, a reformed Titan imprisoned by Nyx, the primordial goddess of night. As their journey progresses, Nico and Will realize that everyone has both light and dark inside. They must accept these dual aspects in themselves and others to work through the traumas and emotions that affect them and their relationship, to survive in Tartarus, and to rescue their friend.

The Sun and the Star was a number one New York Times Bestseller and is on Barnes & Noble’s list of “The Best Books of 2023 (So Far).”

This guide refers to the 2023 Disney Hyperion hardback edition.

Content Warning: The source text includes frequent discussion of mental health conditions, including post-traumatic stress disorder (PTSD) and eating disorders. While this book provides positive representation of gay and bisexual identities and relationships, it includes mentions of anti-gay bias.

Plot Summary

Nico di Angelo, the demigod son of Hades, dreams about the most traumatic moments in his life and hears a voice call to him from Tartarus, the deepest part of the Underworld. The voice belongs to Bob the Titan, who previously sacrificed himself to save Percy Jackson and Annabeth Chase. Nico and his boyfriend Will Solace, a son of Apollo, receive a prophecy to rescue Bob. They get advice from Percy and Annabeth, who know how deadly Tartarus is.

When they try to enter the Underworld, Nico and Will get trapped in a cycle of nightmares by Epiales, the god of nightmares and a child of Nyx, the personification of night. They eventually escape when Will discovers the power to shoot a beam of pure light that can defeat creatures of darkness.

Nico thinks he is nothing but darkness and negative emotions, while Will is entirely light. Will makes unfair assumptions that life and light cannot be found in darkness, which hurts Nico, who thinks Will doesn’t accept him for who he is. Will’s mind starts to change as they interact with beings in the Underworld. The troglodytes, a subterranean humanoid frog species, help them find the way into Tartarus, where Will has a discussion with Nico’s stepmother Persephone. Persephone gives him advice on how to love someone from the Underworld and how to accept the darkness within. Despite this, the Underworld affects Will physically and emotionally: he is often weak, disoriented, and forgetful.

The chapters that detail Nico and Will’s progress through the Underworld are interspersed with flash forwards to their conversation with a nymph named Gorgyra, to whom they recount happy memories of their relationship. Though they think they’re offering stories in exchange for use of her boat, she knows that these positive memories will make them strong enough to survive in Tartarus. When the main storyline catches up to these flash fowards, Nico and Will descend to Tartarus in Gorgyra’s boat.

They are immediately overwhelmed by the despair and pain of Tartarus. They fight creatures named cynocephali. After a confrontation with Amphithemis, a personification of “mania,” Will and Nico argue about Will using Amphithemis’s vulnerability and suggestibility to save them. Nico is angry that Will took advantage of a vulnerable spirit who can’t help being the way he is.

As they work their way through Tartarus, they resolve similar conflicts with clear communication and accountability. They’re guided by Bob’s cat, Small Bob. Small Bob leads them to Nyx’s Garden, where Bob is trapped in a permanent cycle of regeneration. Bob used to fight against demigods under the name Iapetus; Nyx hates change and wants him to be Iapetus again. When Will and Nico free Bob from his regeneration blister, it is clear Bob accepts his past as Iapetus, but has no desire to return to that identity.

In the fight against Nyx, Will begins to accept his darkness while Nico begins to accept his inner light. Nyx has made “cacodemons,” or personifications of Nico’s negative emotions, but Nico is ready to let go of his demons and the power they have over him. He frees the cacodemons, which he renames “Cocoa Puffs.” Nyx’s children, tired of being exploited by her, restrain her while Bob and the demigods escape down the river in Gorgyra’s boat.

Nyx tries to attack them once more, but she withers when she touches the Acheron, the River of Pain. This is because—unlike Will, Bob, and Nico—Nyx refuses to change. The Cocoa Puffs decide they want to leave Tartarus, so they climb in the boat once Nyx is defeated. Nico and Will have learned that you cannot escape from your negative emotions or the traumatic events of your past. Instead, you must accept them and learn to live with them.

Bob pilots them to Camp Half-Blood. He and Small Bob begin their journey west, glad to now have the freedom to choose their future. Nico and Will’s relationship is stronger than ever after their journey. Will learns that he doesn’t have to heal Nico’s darkness, and Nico learns that he doesn’t have to hide his dark parts from Will or be afraid of the light.