For his tenth birthday, Joe receives a mysterious blue book from his magician uncle and namesake, "Joe the Magnificent," known only as The Book. Using an often unpredictable number of voice and print clues, The Book transports Joe and his friends Fred and Sam to a variety of different times and places, from Camelot's medieval court of knights and dragons to the year 2105, where they meet their own great-granddaughters. The only way they are able to return present-day Brooklyn, New York is to find The Book again within whatever time period they are in. Later in the series, Joe's evil uncle, Mad Jack, makes several attempts to capture the children and The Book with his crafty tricks, whether stranding them in Antarctica (where the book doesn't work) or trying to make their new home in China (during the Tang Dynasty).