The Z warriors are extremely concerned. Everybody on earth is hysterical, the Earth is about to be destroyed by a comet, and enormous that was detected by satellite. It's approaching Earth at a relatively quick speed, and the only people who can prevent it are Earth's special forces: The Z warriors. Gohan meanwhile meets with Piccolo at a riverbank. He whistles and waltzes, and the high audibility put in the whistling irritates Piccolo because of his ear, it is very sensitive, so are all the other Nameks. Piccolo demands Gohan to stop, and insists for both of them to go see what Goku is doing.

On the day of the comet impact, Krillin, Gohan, Goku and Piccolo stand and try and stop the comet from hitting Earth. Goku sends an enormous kamehameha wave towards the meteorite, but it has no effect. When everyone is helpless and all is lost, the comet enters the Earth's atmosphere. But instead of striking the planet, it emits a spaceship on to the planet and then the comet steers itself away and into space, sightless. The spaceship lands on Earth with a great smash, the thud and the emphatic hit develops a crater. The Z warriors go to investigate the scene, so does everyone else.

The ship consists of many people. These people are devious, evil people. They are all servants of a tyrant named Lord Slug, a Namekian immigrated via a comet to Earth to conquer. Lord Slug emerges from the ship, and the police/FBI, whatever, start to shoot at Slug's minions. But the bullets coming from the barrels are all reflected. Slug sends his troops to kill every bystander. But Gohan and Piccolo kill all the minions. Krillin and Goku got caught and trapped on an icefield, so they cannot help Gohan and Piccolo. The minions are killed, and the henchman of Slug is left. Piccolo is knocked unconscious from the minion battle and Gohan, with no assistance is forced to yield to the henchman. Slug places a hand on Gohan's small head and reads his mind. Slug finds out about the dragon balls and its capabilities, so he decides to search for them. But the only issue is that Slug needs to know where they are. Bulma arrives and gives Piccolo a senzu bean, healing him and Piccolo comes back to consciousness. She also heals Gohan, and she asks whats going on. Slug informs her that he's in search for the dragon balls, and she stupidly tells him that you require the Dragon Radar to find them. The henchman of Slug immediately captivates her, and Slug reads her mind also.

He finds out where the Dragon Radar is, and he sends his troops to find it. They find it and return with all seven-dragon balls and summon Shenron. Shenron grants Slug one wish: to make Slug young again, since Slug is much weaker when he is old and much more slow. In his young state he is more agile and powerful. Slug has used up his wish, and he orders his troops to kill Gohan and Piccolo.

Meanwhile at the icefield Krillin and Goku escape from the trouble they got themselves in and arrive at the battlefield to find Gohan and Piccolo unconscious. Goku and Krillin, with their fresh legs are able to destroy the henchman. The battle with the henchman evicts Krillin from the field, because he is exhausted and unable to fight.

It is now Goku vs. Lord Slug. The conflict is equal, until lord Slug enlarges his body, just like Piccolo did in DB. Slug's power is up to its fullest extent, and he begins to bash Goku to a pulp. Slug reveals himself, he is a Namek. This gives Piccolo an idea. Piccolo screams at Gohan and asks him to whistle, just like he did at the start of the movie(I didn't write that whistling scene for nothing, it's relevant.) Gohan whistles loudly, and Piccolo rips his own ears off to avoid the pain. Slug is irritated by the level of noise, and staggers.

In the commotion Goku obtains energy from Krillin, Gohan and Piccolo, generates a Spirit Bomb, and throws it at Slug and in the catapult Slug is killed. The world is saved and everything becomes justice.