Resumen
After a break from their trips in the tree house, Jack and Annie are delighted to find that its back! Morgan le Fay needs their help, but theyll have to become Master Librarians first, and that means solving four riddles. For the first one, Morgan sends them deep into the middle of the ocean. Jack and Annie ride in a mini-sub and meet jellyfish, sea horses and an octopus. But there are some scary sharks in the deep and the friendly dolphins have to come to the rescue...
