Thea Stilton

"Mouseford Academy students are taking a special hot-air ballon tour of Whale Island and beyond, but when they pass over Turtle Island, they see a lack of turtles and a whole lot of trash! And for once, the selfish Vissia de Vissen seems worried about this mysterious disappearance too! In order to solve this riddle, Colette, Nicky, Pamela, Paulina, and Violet will have to do the impossible--team up with Vissia de Vissen and her children Vic and Vanilla! Will they be allies--or are they still enemies?"--Back cover.