Race To The End Of The World And Beyond Once again it is up to our two boy heroes Shawn and Jimmy to save the world. A massive comet headed towards Earth must be stopped before crushing the planet. And it seems that the only hope for all mankind are The Gravity Boxes. The problem being that before the boys can go into action they are thrown back into the 12th century by the Professor's new time travel machine. Upon arriving in the past the boys are immediately accused of being witches and sentenced to death. Before they can save the planet they must battle an evil black knight, escape the dungeon, the executioner, and recover the time travel device. If all goes well they might have a chance of returning to their own time to keep the world from being squashed by the giant comet. It seems that the boys have a busy day ahead of them, and after that they still have to get to the Gravity Boxes.