The Mystery in the mall: The Aldens are working at a mall owned by their grandfather's friend. Some merchandise bound for Penny's emporium has disappeared. What's going on at the Hope Harbor Mall. The Black pearl mystery: The Aldens are visiting Hawaii, where they help pick pineapples on their cousin Mary's plantation. There's a mysterious legend about a black pearl, but no one will tell them the story. The Mystery cruise: Grandfather's taking the children on a wonderful cruise in the Caribbean! No sooner has the cruise begun than things start to go wrong. Is someone tampering with the ship?