Ok, here's the deal. Say you're and alien from the planet Vegeta, born with the ability to transform by the power of the full moon as long as you have your tail. You were sent to Earth as a baby, with the mission to enslave the world as you grew older and stronger. Well, that didn't exactly happen, you were taken in by a kindly man named Gohan, and you weren't exactly a little angel to him, in fact, you hated him, and everybody. Until one day you were walking with him, and you fell into a ditch and bumped your head. After you recovered, you were the sweetest little boy, but had acceptional powers because of your race.
As you grow up, you do many things, among them getting your tail permenantly removed, because, with a tail you have the ability to transform, but you also have a huge weakness. If anyone grabs your tail you feel unbearable pain and become frozen where you are.
Well, you get married, and have a son. Look at that! He has a tail, he must be just like you.
Just when you think life can't get any better, you're evil brother Radditz comes from Vegeta to check your progress, and try to get you to join his side. But, since you don't, he captures your son and says if you don't he'll just take your son Gohan.
To stop him, you're forced to team up with your arch-enemy Picollo, but the only way you could destroy him was to hold onto him and let Picollo destroy you both, but for Earth's sake, you do it.
Now your friends need to collect all 7 magical dragon balls and wish you back to this dimension.
Sound fun? Just an average day in the life of Goku, the world's most powerful hero.
Well, this was really just the beginning. So much happens in the story.