The forces of Earth are once again faced with a new threat.

A mysterious fighter has arrived on Earth, and his name is Radditz. His goal: retrieve his brother, the Saiyan baby Kakkarot (known on Earth as Goku), who should have taken over Earth by now. But another evil force, Piccolo, has sensed Radditz and does battle, only to discover how weak he is compared to this mysterious Saiyan!

As Goku and his son, Gohan, head over to Master Roshi's for a visit, they are attacked by Radditz. Goku is beaten easily but Radditz chooses not to kill him. He merely kidnaps Gohan and heads off, telling Goku he'll get his son back if he chooses to join the Saiyan army, but Gohan will die if he doesn't.

Preparing to head off for battle, Master Roshi stops him, telling Goku he's not strong enough to defeat Radditz alone. But that’s when Piccolo shows up. Even though they are enemies, Piccolo suggests a temporary partnership, which will end the second Radditz is killed. The two fly off to find Radditz.

Meanwhile, Radditz is picking up an enormous power level and all signs point to Gohan. Radditz merely ignores the scouter, believing it to be broken.

That's when Goku and Piccolo show up. The two appear to be losing until Piccolo discovers Radditz's weakness: grabbing his tail. Goku gets a good grip, but surrenders his grip when Radditz claims to be apologizing. Radditz is lying, or course, and begins to crush Goku's ribs. Gohan, hearing his father's cries of pain, breaks out of Radditz's ship and attacks Radditz out of anger. The attack is very powerful, but Gohan's power level is gone in a matter of seconds, along with his memory of the encounter.

Goku gets up as Piccolo powers up for a special attack, the Beam Cannon. Realizing Radditz is too fast for Piccolo to attack, Goku jumps behind Radditz and grabs him, holding him still for Piccolo. For Radditz it means death. For Goku, it means death.

For Goku's enemy, Piccolo, it is far too convenient. And with that, Piccolo attacks Radditz and kills the evil Saiyan, but Goku is killed as well.

After the battle is over, Master Roshi, Krillin and Bulma arrive at the fight. Piccolo tells Radditz that he lost, because Goku will be resurrected with the Dragon Balls. Radditz tells him that he hasn't lost: his scouter is a communicator too, and two other Saiyans will arrive in one year and resurrect him with the Dragon Balls. And then, Radditz dies.

Goku gives his last words, and then dies, only to mysteriously disappear! Piccolo tells them it's because of Kame, but then tells them that Gohan may be there only hope and disappears with the boy in tow. Gohan's mother Chi-Chi is not too happy about it…

Goku awakens at the Earth Check-In station, where dead souls are sent. There, Kame tells him that he will travel along the Snake Way path until he finds King Kai, who will train him in the arts of Kaio Kin. Kame will remain on Earth, training other fighters. So Goku sets out. Over the course of six months, Goku went through quite a bit. He was almost eaten by the evil Princess Snake (whom he refused to attack after she had been kind enough to give him an enormous meal) and eventually wound up…at the beginning! He then set out again and, at the end of 6 months, finally reached King Kai's place.

Back on Earth, Piccolo has taken Gohan under his wing, training the young boy to be a fighter. After Gohan survived a training course where the boy was alone in a deserted area, he finally reached home. But upon seeing his mother, he decided that the Earth was in too much risk to end his training now. He then returned to Piccolo, whom he asked to train him.

Back on King Kai's "planet", Goku is undergoing rigerous, yet humiliating, training. After catching King Kai's pet monkey Bubbles, Goku is given a hammer and told to hit a small cricket, Gregory, with it. But first, a quick meal.

It is during this meal that King Kai tells Goku the legend of the Saiyans. On a planet hundreds of years ago, there were two races: a small, technologically advanced race called the Tuffles and the large, brutish Saiyans. After years of fighting between the two, it looked like the Saiyans were doomed. Then, something happened that only happens once every couple thousand years.

The moon turned full.

As the Saiyans transformed into large, brutish, Oozarus, they clearly had the upper hand. By morning, the Saiyans were all that were left on the planet. Then, the guardian of the planet stepped in. Ashamed by the Saiyans, he called forth a hail of meteors which destroyed the planet, as well as all the Saiyans, except for four. Those four were off on distant planets thanks to the technology the Saiyans had been able to use for the short while. The four infants landed in different planets, where they would grow to take over their planets for the Saiyan race. One pod landed on Earth. In this pod was the young Saiyan Kakarot. He grew to be known as Goku.

Disturbed by the thought of how strong and powerful the Saiyans were, Goku stood and told Jeremy to get ready to go outside: they needed to resume training.

But on Earth, time grows short. As Tien, Yamcha, Krillin, Chaotzu and Yajirobe train on Earth, Gohan and Piccolo continue to train. After already destroying the moon to present Gohan from transforming any farther, Piccolo is amazed when it returns the next night. He tries to destroy it, but his attack goes right through the moon! He comes to discover it was a hologram produced from the remains of Goku's crashed pod.

Back on King Kai's Planet, the time for training is over. As Goku proves to King Kai what he can do, he prepares to return to Earth. King Kai tells him that he has no way of getting him back immediately, but he's much faster now, so it should only take him 2 days. Unfortunately, that's still one day too late!

On Earth, the Saiyans have arrived. Nappa and Vegeta are truly fearsome, though Nappa is the only one fighting. Before the fight, however, Vegeta pulls out a trick and unleashes 6 small green fighters called Saibamen on the Earth Special Forces. Yamcha attempts to defeat one of them, but it turns out that it's kamikaze. Yamcha is killed when one grabs onto him and blows up. Upon realizing that they are too weak to defeat the fighters, Vegeta kills the remaining Saibamen himself.

Now Nappa steps in. Tien attempts to defeat him, but is nowhere near strong enough. In the process, Tien loses a hand. Chaotzu jumps Nappa and attempts to kill him by blowing himself up, but fails. Enraged, Tien goes all out and attacks the Saiyan with everything he's got. He does inflict some damage, but it costs him his life. Powerless and helpless, Tien dies from exhaustion.

As Piccolo, Krillin and Gohan continue to fight, Goku is making great progress. But it seems he will not make it fast enough.

When Nappa attempts to kill Gohan, Piccolo jumps in to stop him. Unfortunatly the blast kills Piccolo, who tells Gohan of their last hope now that he is dead. Since Kame and the Dragon Balls will disappear with Piccolo, he tells them to fly to Namek. Once there, they can use the Namek Dragon Balls to wish everyone back.

Furious, Gohan attacks Nappa, but is swatted away like a fly. Just as Nappa prepares to kill Gohan, he disappears. Suddenly the shape of a cloud appears, and Gohan is sitting atop Goku's flying nimbus! Standing solemly, Goku gives Gohan and Krillin half of his last senzu beans, a gift from Corrin, and confronts Nappa, whom he defeats with great ease. Insulted by how weak his comrade is, Vegeta kills Nappa.

Now sensing just how strong Goku is, Vegeta removes his scouter and enters into the fray himself. The two engage in a massive battle when Vegeta flies up and powers up a blast strong enough to destroy the Earth! Goku counters with a Kamehamea Wave using the double Kaio Ken, but it's not strong enough! Breaking his promise to King Kai, Goku powers up to the Triple Kaio Ken, then the 4x Kaio Ken! Unfortunatly, it leaves Goku nearly powerless.

Sensing he is near defeat, Vegeta creates a small moon and hurls it into the air, then looks at it and transforms into an Oozaru!

Realizing he has only one hope left, Goku uses Tien's Solar Flare technique and flies away, giving himself enough time to create a Spirit Bomb! Unfortunatly, Vegeta recovers sooner than Goku anticipated, and attacks Goku, who drops the spirit bomb and hurts himself more than Vegeta. Battered and bruised, Goku is helpless as the 60-foot tall Vegeta crushes him like a bug, shattering most of his torso and breaking both his legs.

But Krillin and Gohan return just in time to help Goku, as Yajirobi runs away, apparently in fear. As Gohan distracts Vegeta, Goku gives Krillin the remaining energy from his spirit bomb when, much to everyone's surprise, Yajirobi intervenes and removes Vegeta's tail! Now a normal Saiyan, Vegeta is about to attack Gohan when King Kai contacts Krillin and tells him to throw the spirit bomb. The bomb misses Vegeta the first time, but Gohan is able to deflect it and make a direct hit. Vegeta returns, incredibly ticked off, and destroys nearly everything when Gohan catches a glimpse of the mini moon. Gohan transforms and instinctively goes after Vegeta. Vegeta is able to remove his tail, but miscalculates and is unable to get out from under the falling Gohan, who crushes him just before transforming. Krillin grabs Yajirobi's sword and is about to kill Vegeta, but Goku stops him and they allow Vegeta to escape.

Within a matter of moments of Vegeta's departure, Bulma, Roshi, and the others arrive to take the beaten heroes to be healed, but without the Dragon Balls they have a new goal...the planet Namek.