"Pearl and Periwinkle" is a children's book written by Anna Graetz. Unfortunately, there isn't much information available about this specific book, and it seems to be relatively obscure.However, based on the title, "Pearl and Periwinkle," one might speculate that the story could involve characters named Pearl and Periwinkle who embark on an adventure together. The names suggest a whimsical and perhaps maritime theme, with potential for exploration, friendship, and discovery.