With no new battles to fight, Goku has been living a quiet life in the countryside with his wife Chi-Chi and their son Gohan. While at a reunion with his friends, Goku is visited by his evil Saiyan brother, Raditz, who then kidnaps Gohan and keeps him hostage.
Goku and Piccolo team up to defeat Raditz and rescue Gohan, but their combined power is not enough. Gohan, while being locked in Raditz's space pod, is showing incredible power levels, which Raditz finds hard to believe.
Raditz manages to disarm Piccolo, literally, and is able to survive Goku's special technique, the Kamehameha. Gohan then breaks out of Raditz's space pod and with his power raised by his anger, bashes into Raditz, giving Goku the time to grab onto him and allow Piccolo to charge up his new technique, the Special Beam Cannon.
Piccolo hits both Raditz and Goku with his Special Beam Cannon, killing them both. Before he dies, Raditz reveals his two Saiyan partners, Vegeta and Nappa will arrive on Earth in one year. Piccolo then takes Gohan to train him, while Krillin is sent to tell Chi-Chi of the recent happenings. In the Other World, Goku is sent to King Kai to receive training in preparation for the Saiyans.
One night during training, Gohan gazes at the full moon and transforms into a Great Ape. Before he causes any serious damage, Piccolo destroys the moon, which turns Gohan back to normal, removes his tail, preventing him from transforming again, and then leaves him to fend for himself. A message from Yajirobe tells Krillin to go train at Kami's Lookout, and to bring Yamcha, Tien, and Chiaotzu along with him.
Gohan befriends a Brontosaurus, but loses it to a hungry Tyrannosaurus Rex. Meanwhile, Krillin and Bulma find Yamcha at one of his baseball games.
On their way to Earth, Vegeta and Nappa land on Planet Arlia and are arrested by the ruler's soldiers. They later help free all of the prisoners and overthrow the king. Afterwards, they destroy the planet and continue to Earth.
On his way to King Kai's planet, Goku accidentally falls off Snake Way and lands in the Home for Infinite Losers (H.F.I.L) where he meets two ogres, Goz and Mez. After beating Goz in a wrestling match and Mez in a speed match, the two ogres shows him a secret passage that leads to the beginning of the Snake Way.
Goku comes across a house on Snake Way and a beautiful woman named Princess Snake tries to kill him without him knowing it.
Gohan tries to escape from Piccolo's harsh training and get home to his mom, without Piccolo finding out. Along the way, Gohan tries to save some orphans from going to an orphanage. Note: This episode was skipped during Dragon Ball Z's original 1996-1998 run in syndication due to concerns over its content, although it was later aired on Cartoon Network.
Kami puts Krillin, Yamcha, Tien, and Chiaotzu in the Pendulum Room, where they fight against two Saiyans, who beat the Z-Fighters, but are told by Kami the two Saiyans were not as powerful as the ones on their way to Earth.
Goku reaches the end of Snake Way and meets King Kai; meanwhile, Gohan once again becomes a Great Ape and Piccolo finds Goku's old space pod projecting an image of the full moon. He then destroys the pod with his Special Beam Cannon, turning Gohan back to normal, and removes his tail again.
Goku's first task is to make King Kai laugh. Once that's done, he is told to catch Bubbles, King Kai's monkey. With the increased gravity on King Kai's planet, it is harder than it looks.
Goku's next task is to hit Gregory, King Kai's grasshopper, with a hammer. While taking a break, King Kai tells Goku the legend of the Saiyans and his connection to the warrior race.
Goku completes his training, learning the Kaio-ken and the Spirit Bomb, but the Saiyans finally arrive on Earth. Goku is wished back to life and rushes down Snake Way, but unfortunately, it will take him two days to reach the battlefield.
While Goku races down Snake Way, Piccolo, Gohan, Krillin, Yamcha, Tien and Chiaotzu battle with Nappa's Saibamen, each of whom are as strong as Raditz.
The battle with the Saibamen continues, and Yamcha is killed when one of them self-destructs on him. An enraged Krillin kills the rest with one blast. Now, it's Nappa's turn.
With all of the Saibamen killed, Nappa steps into the battle and attacks Tien, who loses his arm to the Saiyan. Chiaotzu is killed when he tries and fails to kill Nappa by self-destructing. The battle continues as Goku makes his way back to Earth.
Enraged at Chiaotzu's sacrifice, Tien fires his Tri-Beam at Nappa, using all of his energy, and dies. Nappa, unharmed, continues his onslaught against the remaining Z-Fighters. Vegeta tells him to stop and gives them three hours for Goku to show up. Nappa spends the time killing the news crew.
Three hours have passed and Goku still hasn't arrived on the battlefield. Vegeta allows Nappa to start attacking the remaining Z-Fighters again. Meanwhile, Goku arrives on Earth and heads to the battlefield on the Nimbus Cloud.
Nappa tries to kill Gohan with a blast, but Piccolo jumps in the way and is killed, along with Kami and the Dragon Balls. Goku arrives on the battlefield in time, and starts fighting with Nappa. Soon, the powerful Nappa finds himself overwhelmed by the even more powerful Goku.
Goku continues to humiliate Nappa, until Vegeta tells him to give up. Nappa then moves in to attack Gohan and Krillin, but Goku uses his Kaio-ken and plows into Nappa, critically injuring the Saiyan. Enraged at his partner's weakness, Vegeta kills the weakened Nappa. Goku and Vegeta then begin to fight.
Vegeta is the superior at the beginning of their fight, and not even the Kaio-ken x2 is enough for Goku to gain the upper hand. Desperate, Goku uses the Kaio-ken x3 and overpowers Vegeta. Enraged, Vegeta attempts to destroy the planet with his Galick Gun, but Goku counters it with his Kamehameha and overpowers Vegeta's blast by adding the Kaio-ken x4. Still angry, Vegeta creates an artificial moon and transforms into a Great Ape.
As a Great Ape, Vegeta begins toying with Goku. Goku tries to hit him with a Spirit Bomb, but Vegeta notices and blasts him before he can.
Yajirobe cuts off Vegeta's tail, reverting him back to normal form, and Gohan takes his dad's place in fighting him. Meanwhile, Goku uses the last of his energy and makes a Spirit Bomb and gives it to Krillin. Krillin throws it at Vegeta, but he jumps over it. Gohan blocks it back and it hits Vegeta, but he survives the attack.
Gohan looks at the artificial moon and unknowingly becomes a Great Ape again. He attacks Vegeta, until the Saiyan Prince cuts his tail off, but Vegeta is crushed by Gohan while reverting back to normal, and is finally defeated. Krillin tries to kill him with Yajirobe's sword, but Goku convinces him not to, believing that Vegeta will learn to change his evil ways just like Piccolo did, and Vegeta escapes in his space pod.
Goku, Krillin, and Gohan are brought to the hospital after their battle against the Saiyans. Meanwhile, Bulma and Mr. Popo find Kami's old ship, which he used to come to Earth from Namek, his home planet. She prepares to go there while the others rest.
Bulma is arrested by a mysterious group of militant, heavily armed refugees while traveling to Namek. At first, they accuse the trio of being henchmen of the evil Frieza that destroyed their home planet. However, when the Earthlings help in a dangerous situation, the refugees allow them to continue on their journey to Namek. They reach the planet and, with the help of two Namek natives, begin their search and find two Dragon Balls.
Bulma is arrested by a mysterious group of militant, heavily armed refugees while traveling to Namek. At first, they accuse the trio of being henchmen of the evil Frieza that destroyed their home planet. However, when the Earthlings help in a dangerous situation, the refugees allow them to continue on their journey to Namek. They reach the planet and, with the help of two Namek natives, begin their search and find two Dragon Balls.
On Namek, Bulma, Gohan, and Krillin continue their search for the Dragon Balls with the help of the Namekians. On Earth, Goku starts his training early even though he has not yet healed, while far away in the universe, Vegeta finishes his recovery at one of Frieza's bases.
Bulma, Gohan, and Krillin discover that they are not on Namek, but a planet where the two Aliens are trapped. They plan to steal Bulma's ship. On Earth, Goku finds that he has not fully recovered from his injuries and is taken back to the hospital by Chi-Chi and Master Roshi.
After escaping from the aliens, Gohan, Krillin and Bulma land on Namek. Already there, Vegeta, Frieza, and his henchmen are also looking for the Dragon Balls.
Frieza's men destroy Bulma's ship, stranding them on Namek. Krillin and Gohan in return take down the henchmen. Meanwhile, Vegeta fights with and kills his rival Cui, another one of Frieza's henchmen.
Goku fully heals, thanks to a Senzu bean from Yajirobe. He then breaks out of the hospital and leaves for Namek in a rebuilt version of his old Saiyan space pod, built by Dr. Briefs. Meanwhile, Gohan and Krillin watch as Frieza invades a Namekian village.
Gohan and Krillin continue to watch as Frieza's henchman Dodoria slaughters the Namekians in their village.
Gohan and Krillin take action and save Dende, a Namekian child, from being killed by Dodoria. He chases after them, but they escape.
Vegeta fights with Dodoria and forces him to tell what really happened to his homeworld, Planet Vegeta. Dodoria reveals that it was Frieza who destroyed it, and then Vegeta kills him.
The side of Goku's ship is cracked, and it is heading straight toward a star, but he uses his Kamehameha to propel himself back on course. Meanwhile, Vegeta wipes out a Namek village and takes a Dragon Ball.
The side of Goku's ship is cracked, and it is heading straight toward a star, but he uses his Kamehameha to propel himself back on course. Meanwhile, Vegeta wipes out a Namek village and takes a Dragon Ball.
Vegeta fights with Zarbon, another of Frieza's henchmen, and is winning until he transforms. His power greatly increased, Zarbon toys with Vegeta before knocking him out.
Dende takes Krillin to Guru, the eldest Namekian. Guru gives Krillin a Dragon Ball and unlocks his hidden potential, which makes him much stronger.
Frieza orders Zarbon to retrieve Vegeta, while Yamcha, Tien, and Chiaotzu begin their real training in the Other World with King Kai.
Frieza heals Vegeta, but he escapes and steals all of Frieza's Dragon Balls. Vegeta then finds Krillin with a Dragon Ball and begins pursuing him, with Zarbon in chase.
Vegeta and Zarbon begin fighting again. Vegeta, who is stronger thanks to his Saiyan recovery cells, defeats Zarbon. Meanwhile, Goku gets stuck in a magnetic storm while training at 100x gravity and struggles to shut the gravity machine off.
Vegeta finishes off Zarbon and steals Krillin's Dragon Ball. He then runs into Gohan, but fails to notice that he is also hiding a Dragon Ball. Gohan brings it back to Bulma and Krillin. Meanwhile, Frieza orders his elite fighters, the Ginyu Force, to come to Namek immediately.
Bulma drops the Dragon Ball in the water and gets in a mini-sub to get it back, but it has settled in a giant crab's clutch of eggs, and she has to fight the crab to get to it.
Bulma is captured by two of Frieza's soldiers, but she tricks them into thinking there are lots of Dragon Balls in the crab's egg clutch. They try to steal them and the crab kills them.
Vegeta and Krillin fight, while Gohan's potential is unlocked by Guru. He returns to help Krillin. Meanwhile, Frieza's fighters, the Ginyu Force, arrive on Namek. In space, Goku finishes his training at 100x gravity and is surprised by his newfound power.
Frieza introduces the Ginyu Force, and Vegeta is forced to team up with Gohan and Krillin. Captain Ginyu steals the Dragon Balls, while Gohan and Krillin prepare to fight Guldo, the weakest member of the Ginyu Force.
Guldo uses his psychic time freezing powers to fight against Gohan and Krillin by freezing them in the air. While they are frozen, he prepares to throw a tree at them, but Vegeta kills him before he can.
Vegeta attacks Recoome, the second member of the Ginyu Force, but he is unable to win. Recoome eventually defeats him before proceeding to challenge and defeat Krillin. Note: This episode was originally titled The Relentless Recoome.
Frieza finally obtains all seven Dragon Balls, but realizes that he needs a password to use them. Meanwhile, Gohan fights Recoome and puts up a good effort, but Recoome is far too strong. Eventually Gohan is defeated when Recoome breaks his neck. Though it seems the end is near however, Goku finally arrives on Namek and heals Gohan with a Senzu Bean.
After also healing Krillin and Vegeta with Senzu Beans, Goku challenges Recoome. Recoome believes he is just facing another weakling, but is quickly proven wrong when Goku defeats him with just one blow. As the remaining Ginyu Force members, Burter and Jeice, fight Goku, Vegeta begins to suspect that Goku is the first Super Saiyan to emerge in 3000 years.