The Book is a blue hard-covered book used to store historic data, and can be used to time travel.
In many episodes, the Book is being watched and stolen by the antagonist leaders. Mad Jack desired the Book to rule all of eternity. Other antoganists would try to rule the world or win battles which can also be bad for the world. Another reason it was to be taken back by the Time Warp Trio was to get back home.
Whenever the kids make a wish, the Book emits a glowing green mist and warps them back through time. Whether they want to go or not, they are thrust into an extraordinary adventure, in which they duel with gladiators in ancient Rome, or meet Blackbeard the pirate on the open seas! One time, the boys are accidentally warped into the future, where they meet their own great-granddaughters who live in the year 2105 and also go on adventures using the Book, which they have inherited. The Book has been passed down from many generations and Joe's great grandfather once owned the book.