Dragonball GT is the sequel to Dragonball Z. The GT stands for Grand Tour and was orignallly seen as a road trip. GT starts of with Goku's enemy from Dragonball, Emperor Pilaf finding the "Black Star Dragon Balls" which
are Dragonballs with the stars black and are more powerful than the orignal Dragonball also these balls must be gathered back to the Earth or it will be blown up. The problem is the Blackstar Balls spread across the universe. Also Pilaf wishes Goku to be turned back into a child.