In "The Hidden Oracle," the first book of Rick Riordan's Trials of Apollo series, the main character, Apollo, is transformed into a mortal teenager named Lester Papadopoulos as a punishment by Zeus. He must navigate the challenges of being human while trying to reclaim his divine powers. Along the way, he faces various mythical creatures and struggles with human emotions, all while seeking to help the demigods at Camp Half-Blood.

The quote "They have gone missing? No, no, no, no, no, no, no. No, et cetera" reflects Apollo's frantic nature as he confronts the gravity of the situation, highlighting his humorous yet desperate attitude toward the challenges he encounters. The storyline is filled with action, humor, and an exploration of themes like redemption and the importance of friendship. Apollo's journey is not just a physical quest but also a path towards understanding himself better.