From the World of Percy Jackson: The Court of the Dead (The Nico Di Angelo Adventures)

A BRAND-NEW ADVENTURE FROM THE WORLD OF PERCY JACKSON AND THE OLYMPIANS
New York Times #1 bestselling authors Rick Riordan and Mark Oshiro collaborate again on a new adventure in which demigod Nico di Angelo teams up with his half-sister Hazel Levesque to protect . . . monsters?
A few months after returning from the depths of Tartarus, demigods Nico di Angelo and Will Solace agree to join Nico''s half-sister Hazel Levesque at Camp Jupiter on the West Coast. She needs their help in managing a situation that the boys inadvertently brought about: the demigods showed the monsters of the Underworld that they have options; they don't have to be evil.
Now some of those monsters have taken up residence at Camp Jupiter to seek refuge. Nico and Will are on site, assisting Hazel when one by one monsters start disappearing from camp. A mysterious dark force is at work, and its plan is to punish all monsters for their past crimes.
Things only get worse when Nico, Will, and Hazel learn that they're all connected to it . . .

Rick Riordan (Author)
Rick Riordan (he/him), dubbed 'storyteller of the gods' by Publishers Weekly, is the author of five #1 New York Times best-selling middle grade series with millions of copies sold throughout the world, including Percy Jackson and the Olympians, now a live-action series on Disney+. Rick is also the publisher of an imprint at Disney-Hyperion, Rick Riordan Presents, dedicated to finding other authors of highly entertaining fiction based on world cultures and mythologies. He lives in Boston, Massachusetts with his wife and two sons. Follow him on Twitter at @RickRiordan.
Mark Oshiro (Author)
Mark Oshiro (they/them) is the author of the young adult books Anger Is a Gift, winner of the 2019 Schneider Family Book Award, and Each of Us A Desert, an NPR Best Book of 2020. Their middle grade books include The Insiders, a Publishers Weekly Best Book of the Year; and You Only Live Once, David Bravo. Mark also contributed a short story to the Star Wars anthology Empire Strikes Back: From a Certain Point of View. Mark is based in Atlanta, Georgia and can be found on Twitter @MarkDoesStuff.