The series starts out with Goku having a reunion with Bulma, Master Rochi, and Krillin. He introduces them to Gohan, his five year old son and everything seems peaceful for a change. However, a Saiyan alien lands on Earth to seek Goku. He introduces himself as Raditz, Goku's older brother! Surprised that Goku has not destroyed everyone on Earth, he asks Goku to join him in the Saiyan quest of universal destruction. But, when Goku refuses, Raditz kidnaps Gohan to blackmail
Goku. His command is to kill everyone on Earth. However, Goku remains loyal to Earth and decides to rescue Gohan through another method-- by killing Raditz! Surprisingly, Piccolo allies himself with Goku and the first fight of Dragonball Z begins. After a short time fighting Raditz, Piccolo loses his arm and decides to gather energy to do a super fireball on Raditz. Meanwhile, Goku stalls for time. When
Piccolo is finally powered up, he fires at Raditz, but only grazes his shoulder. Goku then pulls a surprise attack and grabs Raditz's tail. However, the sneaky Raditz fools Goku into believing he will leave the Earth in peace. Once Goku lets go, Raditz starts
beating him up. Once it seems that Goku is doomed, suddenly there is an explosion from where Gohan is being held captive. Gohan suddenly displays his hidden powers and head butts Raditz, breaking his Saiyan armor. Of course, the blow to the head gives Gohan a slight case of amnesia, and he can't remember a thing he just did. After Raditz beats up on Gohan for a while, Goku puts his brother in a hold. At the
advantage, Piccolo powers up and unleashes his fireball, which blasts and hits both Goku and Raditz! Piccolo laughs at the dying Raditz and he mocks him that Goku will be brought back to life through the power of the Dragonballs. Goku's brother retorts
that the device he uses to detect energy levels can also be used for communication. He sends the news about the Dragonballs to his two comrades, and dies.
Because Piccolo discovered that Gohan had hidden powers when Gohan unknowingly head butts and damages Raditz, he takes Gohan from the terrified friends of Goku in an attempt to train him. Goku, rather than retiring in Heaven, is sent on a quest to run on Snake Way and to seek King Kai to receive training for the upcoming fight with the Saiyans. The rest of the Z warriors (Krillin, Yamcha, Tenshin-han, and Chauzu) are gathered to receive special training from Kami.
One year later, Nappa and Vegeta (the evil Saiyans) arrive on Earth. (Instead of deciding to use the Dragonballs to restore their fellow Saiyan, they intend to wish for immortality.) First comes the battle against the Saiba-men (little green monsters) that Nappa planted. The Saiba-men fight, but are eventually killed by Tenshin-han and Krillin. (At one of these fights, Yamcha is killed when a Saiba-man latches on to him and blows himself up.) After the Saiba-men's defeat, our heroes fight Nappa while
Vegeta stands in the background and watches. In a series of battles, Chauzu dies as he sacrifices himself in an attempt to blow up Nappa in the same way the Saiba-man did with Yamcha. Tenshin-han dies by using up all of his strength to try to kill Nappa. On
an impulse, Vegeta calls for a three hour break to wait for Kakarot (Goku), For Vegeta hopes to convert Goku to the Saiyan cause. When the time is up, the fighting resumes without Goku. Piccolo dies when Gohan angers Nappa to where he unleashes a powerful fireball, and Piccolo blocks Gohan with his body. Finally, Goku arrives and easily defeats Nappa using his new Kaio-ken technique. Vegeta sees Nappa's
uselessness and kills him with a single fireball.
Now comes the powerful battle between Goku and Vegeta (Gohan and Krillin are ordered to go away so they won't be held hostage). After a while of smacking each
other, Vegeta faces defeat and decides to blow up the Earth! To save the Earth, Goku breaks his promise to King Kai, by using Kaio-ken times three. Goku and Vegeta shoot two huge fireballs at each other and achieve a stalemate. Goku decides to go even farther and does a Kaio-ken times four. Vegeta is overwhelmed and shot into space as an angry speck. Then Vegeta realizes all he has to do is transform into his
other mode. So Vegeta creates a energy ball that substitutes the moon. Then, he turns into his full moon stage and turns into a giant gorilla. Our hero gets kicked around but blinds Vegeta temporarily. He then gathers energy for his other new technique,
the Spirit Bomb. Unfortunately, Goku doesn't have enough time to throw the bomb at Vegeta. But in surprise move, Yajirobe cuts off Vegeta's tail. Also, the other Z warriors have returned to help. Goku gives his Spirit Bomb to Krillin which misses, and Gohan unwittingly deflects onto Vegeta! Still Vegeta survives. Meanwhile, Gohan's tail grows back. Gohan turns into his full moon stage and kicks Vegeta
around. Later, Gohan gets his tail cut off by Vegeta and finally turns back into a little boy... landing right on top of Vegeta. Vegeta, weary and defeated, crawls to his space shuttle and hovers on the brink of
death as Krillin takes Yajirobe's sword and tries to kill him, but Goku tells him not to. Vegeta laughs and says the have made a mistake, for he will come back for revenge. Slowly he crawls in the shuttle and leaves Earth. But this is not the last we see of
Vegeta...