Ordinary Elementary is anything but ordinary. Below the classrooms are winding, abandoned, underground passages filled with lost treasures. Fifth-grader Graysen Foxx, aka The Gray Fox--finder of secrets, solver of mysteries, and explorer of the unknown--is hot on the trail of the legendary treasure of long-since-retired Principal Redbeard, which includes a decades' worth of confiscated gadgets, rare comic books, first-edition Pokemon trading cards, an original Rubik's Cube, and a retro football handheld video game.

Graysen is determined to find the treasure and share it with his fellow students. His nemesis, Raven Ransom--a fifth-grade girl nicknamed "The Red Raven"--plans to stop him and claim the prizes for herself, just like she did with the game-winning home run kickball everyone thought was lost on the roof of the school.

Wearing his adventurer-iconic fedora, journaling in his field notebook, and wielding his elastic stretchy hand, Graysen is ready for action. But can he avoid the second-grade spy network working for Raven? Could the third-grade twins, Maya and Jack, give him an advantage? Can he avoid the ruthless sixth graders while trying to protect the innocent first graders? And who is the mysterious Midnight Moth who is leaving cryptic notes and riddles?

It's a battle between courage and cunning, smarts and shrewdness, charity and cheating. With the treasure on the line, can Graysen trust his rival--or is it just another one of her traps? May the best treasure hunter win!