Twelve-year-old Mary Lyttle is sitting on the floor of a bookstore when a strange-looking blank book drops into her lap from a shelf above. Moments later, she falls into the book and lands in an earlier time. Relieved that her beloved crystal medallion is still around her neck, she notices an ancient ship anchored nearby. After the captain and his family convince Mary that she must be there for some reason, she boards the ship crewed by talking monkeys...