Something strange is happening at Dragon Elementary. Teachers are whispering, Principal Knight is extra sweaty, and someone swears something was flying above the playground! Ava and Gabby Danger are on the case! Readers in grades 1-4 will help the girls follow the clues and put on their thinking crowns to solve the mystery. Can they figure out what's going on before things get any weirder? Princesses Ava and Gabby Danger love martial arts and putting on their thinking crowns to solve mysteries in their castle, their classroom, and beyond in the Kingdom of Klue. Joined by their sidekick, Erk, a frog they will never kiss even if he might be a prince—ick!—the ninja princess detectives find the clues, follow their hunches, and save the day.