the Vegeta saga starts off showing Goku with his first born son Gohan (named after Goku 's grandfather). Goku takes Gohan to meet the others but as he is doing so another Saiyan warrior (Raditz) arrives on earth and asks Goku why he did not complete his mission at this point Goku is bemused and does not know what Raditz is talking about then Raditz proceeds to tell Goku he is a Saiyan warrior and is Raditz 's younger brother and that he was sent to earth as a child to destroy all life forms on the planet. when Goku refuses Raditz beats up Gohan and tells Goku he has 1 day to kill 1000 earthlings, at this point Piccolo arrives and Goku and Piccolo join forces to track down and defeat Raditz.
Goku sacrifices himself so that Piccolo can defeat Raditz , Piccolo tells Raditz that Goku would be revived by the Dragonballs. Raditz then reveals that his scouter is not only for checking a fighters power levels but also a communicator. he tells Piccolo that 2 more powerful Saiyan 's have heard about the Dragonballs and will arrive in 1 year. Goku is then taken by Kame to see King Yema to see if he is allowed to seek the training of King Kai. At the same time Piccolo takes Gohan to give him training before the Saiyan 's arrive.
When the Saiyan 's arrive the one called Nappa easily disposes of most of the Z fighters alone while Vegeta sits by the sideline watching the fighting. Then Goku arrives and beats up Nappa with ease which annoys Vegeta so he destroys Nappa and fights Goku himself. During the fight there is a difference in the original and remastered release when Vegeta becomes the great ape in the original Goku thinks it is Vegeta who killed his grandfather Gohan and in the remastered version he realises it was himself who killed Gohan (senior). Vegeta is finally defeated and Goku allows him to leave in his spaceship.