Aria, the world traveler, gets invited to a singing competition in Italy. The winning choir will sing for the Pope. Aria, Daisy, and choir members enjoy visiting the Sistine Chapel. After their tour guide tells them a mystery connected to the Sistine Chapel, three choir boys disappear one by one. As Aria and Daisy go on a mission to find the missing boys, they find an unexpected ancient treasure that will help them win the competition. This book series introduces children to other cultures and educates them about the countries Aria visits.