When the king's lucky fishing hat goes missing, so does his luck. Everything is going wrong! But Ava and Gabby Danger are on the case. Readers in grades 1-4 will help the girls and their friends, princes from a neighboring kingdom, follow the clues and put their thinking crowns on to solve the mystery. Can they find Dad's hat before bad luck ruins the family's camping trip? 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.