Dr. Raichi and the Dark Planet arrive in Earth's Solar System, and the souls of those that hate the Saiyans state that they want one more chance to kill them. Raichi announces that it is time to destroy Earth and eradicate the remaining Saiyans.
Soon Mr. Popo arrives at the Son household to speak with Goku and Gohan, he tells them that Dende sent him to tell them that mysterious machines have appeared all over the planet, and they are releasing gas which kills everything around it - plants, animals, and people. Goku and Gohan head off to stop the threat, first stopping at Capsule Corp to talk with Bulma and her father, but Bulma reveals that she is unable to do anything to stop the machines. Mr. Popo then tells Goku and Gohan the location of the machines: Grand Apollon, Western Desert, Bunbuku Island, and the Land of Ice. Piccolo then arrives, stating that he also wishes to help stop this menace, Goku suggests they split up and all go after one machine, and the three Z Fighters each choose an area to head to: Goku will go to Grand Apollon, Gohan will go to the Western Desert, and Piccolo will head to Bunbuku Island. However, two monsters show up (Arbee and Kinkarn) and attack the Z Fighters. Goku attacks them with a Kamehameha, but discovers that the Destron Gas is affecting him and the others, causing them to be unable to properly use their ki attacks. Goku, Gohan, and Piccolo fight the monsters in hand-to-hand combat and defeat them. The three then head to each of their chosen areas.
Goku arrives in Grand Apollon and begins searching for the location of the Destron Gas Machine. Goku goes to the nearby town and asks around if anyone knows about the machine; nobody knows anything but say that there have been strange lights in the west. Goku heads to a large rock formation in the southwest and finds a bird egg, which soon hatches, the bird flies off and Goku follows it, eventually the two arrive at a nest area. The bird tells Goku that it had heard several things while staying on the rock and that there is a machine inside it guarded by another monster, so Goku heads back to the rock, enters and finds the Destron Gas Unit and its guard Ponkarn, Goku fights and defeats Ponkarn and then destroys the Destron Gas Machine.
Gohan arrives at the Western Desert and heads to the local town in order to get information on the Destron Gas Machine; the locals tell Gohan of a pyramid to the south, so Gohan heads there but finds it is too dark to see, so he heads back to the town and is given a flashlight by a man. Gohan heads into the pyramid and finds an inscription stating that there is an even larger pyramid buried under the sand in the southeast. Gohan heads southeast and finds a large sand dune, he inspects it and eventually finds the entrance to the pyramid. Gohan travels through the pyramid and eventually finds a mummy, who requests that Gohan help it unwrap, Gohan manages to unwrap the mummy and discovers that it is in fact a young girl. The girl reveals that she discovered the Destron Gas machine but was wrapped up by the monster guarding it and left trapped in the pyramid. The girl leads Gohan to he machine, where he confronts and defeats its guardian - Jiku - and then destroys it.
Piccolo arrives at Bunbuku Island, but has no idea where to look for the machine and so heads to the nearby town, but they don't know anything so Piccolo heads to several landmarks, including Pilaf's Castle, a large rock area, a lake with a hole in the ground, and Poco Poco Volcano. Piccolo finds nothing at any location until he arrives at the lake, where he meets a pink monster called Kawazu, Piccolo threatens it into revealing the location of the Destron Gas Unit; it obliges, revealing that the machine is beneath the Poco Poco Volcano. Piccolo heads to the volcano but finds that it is too hot to enter, so he decides to head back to Capsule Corp for help from Bulma. Bulma agrees to help, but only if Piccolo helps her with destroying some walls, he does so and she gives him a capsule full of snow to use to cool down the volcano. Piccolo heads back to the volcano and uses the capsule to cool it down, he then heads down and discovers the machine and its guard, who happens to be Kawazu, who he threatened earlier. Piccolo defeats the monster and destroys the machine.
Future Trunks arrives at Capsule Corp looking for Bulma, but cannot find he, Dr. Brief tells him that she is missing but he thinks she will come back. Future Trunks heads off to look for her at Bunbuku Island; he visits each of the islands locations but cannot locate his mother. When he heads to the Eastern Coast and discovers two monsters, he asks where Bulma is and they reveal that she has been taken to an island off the coast in the east; Future Trunks fights and defeats the two monsters and then heads to the island. He finds Bulma and also his baby present counterpart held hostage by more monsters, Future Trunks prepares to fight them, and Vegeta shows up to help him, the two defeat the monsters and then the group head back to Capsule Corp.
Goku and Gohan meet in the Land of Ice, and though Piccolo has not yet arrived, they decide to head out to look for the last machine. They go to a giant control tower in the east and upon arriving are joined by Piccolo. They find the guard who reveals that the last machine is not in the tower, and that the instructions for the machine have already been sent from the tower. The group head to talk to Bulma and then return to the Land of Ice, where they are attacked by an army of monsters; they defeat the monsters and follow their leader southwest to a large rock. Vegeta and Future Trunks arrive, the group then destroy the machine, but it explodes and damages all of them; another army of the monsters (comprised of Gure, Skud, and Bude) attacks the Z Fighters but is eventually defeated. The group are then contacted by Dende, who tells them to head back to West City, as something strange is happening at the television station.
Upon arriving at West City, Bulma tells the Z Fighters that they must head straight to the television station, which is dark aside from four spotlights, revealing four figures: Frieza, Cooler, Slug, and Turles. After the Z Fighters and their past enemies finish talking, they head to a deserted area of the world to fight. First Slug and Turles battle the Z Fighters, only to be defeated, so Frieza and Cooler engage the heroes, only to also be defeated. The villains regenerate and begin the fight again, Turles and Slug attack together, and are defeated, and then Frieza and Cooler attack and are beaten. King Kai then contacts Goku and tells him how to properly defeat the evil warriors. Turles, Slug, Cooler, and Frieza all attack together again and are defeated, but before the group is able to finish them off Frieza launches a huge blast and destroys Bunbuku Island, killing all of the island's inhabitants. The Z Fighters then decide to head offto collect the Dragon Balls in order to bring back Bunbuku Island and its inhabitants, and then head to space to defeat the threat once and for all. Bulma says that to make a space ship for them, she needs some special alien crystals, but they were located on Bunbuku Island, so the Z Fighters are given the Dragon Radar by Bulma, and head off to collect the Dragon Balls.
The Z Fighters head around the world and collect four Dragon Balls, then get the fifth from Krillin, they then head back to West City and find Emperor Pilaf, Pilaf reveals the locations of his two collected Dragon Balls and the Z Fighters collect them. The Z Fighters return to Pilaf and they wish for Bunbuku Island to return, they then collect the crystals and head back to Bulma, who builds a ship for them. The Z Fighters then head to space.
The Z Fighters head to the Dark Planet, but find that it is surrounded by a force field; the ship is damaged by the shield and it crash lands on desert planet. The Z Fighters head to the nearest town and are told by the inhabitants that their elder is in a giant tower that is in the southwest. The elder says that he will help repair the ship if they collect an ancient ring for him. The ring is located in a tomb on the planet and so the group head to it, enter it and begin searching for the ring; they find it in a pyramid inside the tomb, but Frieza is guarding it. The Z Fighters fight and defeat Frieza and then take the ring. The Z Fighters give the ring to the elder, who then helps them repair the ship. The group then head into space again, and contact Bulma to tell her what has happened. The group then spot another ship and decide to follow it to see if the crew know how to get into the Dark Planet.
The Z Fighters arrive at the planet where the ship they were following has landed, it is a planet of water. After they help it, the alien in the ship gives them a device which can help them get onto the Dark Planet. The group then head back to the desert planet for information on the item and are told that it will allow them to travel beneath the sea to a hidden city. The Z Fighters then head back to the fire planet and go to the underwater city. The people there inform them that there is one who can help them get into the Dark Planet, but they were captured and taken to a whirlpool; the Z Fighters head out and save the person, who creates a special orb which can negate the barrier and gives it to them.
The Z Fighters head to the Dark Planet and infiltrate the fortress, defeating Raichi's robotic minions and then confronting Doctor Raichi himself. The Z Fighters battle and defeat Raichi, who then regenerates and attacks again, only to be finally defeated. After Raichi is defeated, his super computer Hatchiyack achieves its humanoid form and attacks the Z Fighters, who fight it, and after a long fight defeat it, finally stopping the Tuffle threat.