Movie 4 begins with Gohan and Piccolo by a waterfall. Piccolo is meditating and Gohan has taught his dragon to dance while Gohan whistles. He decides to show Piccolo. Piccolo then screams out to Gohan to stop. Piccolo then starts to sense something disturbing. Apparently there is some planet come towards earth and the projection shows that the planet would hit earth and destroy it. Everyone starts to panic and worry. Goku and Krillen use a KI blast to change the Planets direction but at the same time not destroy it because Bulma and Dr. Briefs discover that the planet has life on it. They are unsuccessful and the planet continues but it explodes before it does any major damage to earth. But somewhere in the city people begin to surround a spaceship. Out comes an army of weird looking soldiers who said "This planet is now under the rule of lord Slug". Inside the ship they are talking about how long it will take to terraform the earth. Out comes lord slug and he finds out about the dragonballs by reading Bulmas mind and from seeing one from Gohans hat. They go out and find all 7 dragonballs and Lord Slug wishes to have his youth restored so he can be more powerful. Then lord slug orders for the earth to be terraformed. They send out some sort of machine into space right by earth which begins to send out dark clouds that cover the whole entire earth( lord slug and his army can stand the sun). Gohan sneaks out at night to attack the army but there are too many of them. Then out of nowhere piccolo comes to save the day. Then gohan and piccolo must face lord slugs henchmen Dorodabo, Angira, and Medamatcha. Piccolo defeats dorodabo easily but Gohan has some trouble against medamatcha. Just as medamatcha is about to defeat Gohan with a blast guess what happens, Piccolo blocks Gohan and takes the blast AGAIN. Then Goku and Krillen come to the rescue. Goku instantly defeats both Angira and metamatcha. Now Goku must take on lord slug. The battle begins with Lord slug having the advantage. Just when slug is about to finish off Goku, Goku gets a burst of energy and transforms into a super saiyan or something(His hair did not change but there was a gold aura around him). Goku then begins to kick slugs ass. Slug realizes that he cant beat Goku. Then slug reveals that he is a namekian and transforms into a huge giant. Then slug starts to beat up Goku easily, but Piccolo hops on top of slugs head and tells him that he knows his weak points. Piccolo then rips his ears off and tells Gohan to start whistling like he did the other day. He does so and lord slug can't stand it. Then Goku charges up and flies right through Lord Slug creating a hole in the stomach and destroying him. But out of nowhere slug extends his arm and follows Goku through clouds. Goku finds the sun and uses its energy to create an energy bomb which finally destroys Lord Slug and the clouds that have covered the world. Piccolo regrows his ears instantly and that is the end.