In this movie, Frieza’s older brother Cooler is introduced. It begins with a flashback to when Frieza destroyed the Saiyan home world, Planet Vegeta. Cooler’s ship soon picks up a Saiyan space pod on the radar. The pod, carrying a baby Saiyan named Kakarot, is shown to be heading towards Earth, but Cooler’s henchmen believe it is an escape. Cooler lets the ship go, accounting that it’s Frieza’s naiveness, and responsibility. More than twenty years later, Kakarot, eventually renamed Goku, transforms into a Super Saiyan and defeats Frieza on Planet Namek. Despite showing no compassion towards his brother, Cooler takes his Armored Squadron – Doure, Naiz, and Salza to Earth. He plans to kill Goku in order to reclaim his family’s honor. His forces ambush Goku and his friends on a camping trip, and Goku is wounded when he takes a blast from Cooler that was intended for Gohan.
After Krillin sets up a shelter in a cave with Goku, Gohan flies off to obtain Senzu beans from Korin. After obtaining the beans, he is ambushed by Cooler’s henchmen, but is saved by Piccolo. Piccolo dispatches Doore and Neiz, and takes on Salza, easily gaining the upper hand. During the battle, Cooler arrives and catches Piccolo off-guard with a Death Beam, which impales him through the chest but does not kill him. Cooler then sends Salza after Gohan as he continues to blast Piccolo. Gohan gets to the cave with the Senzu beans, but they are destroyed by Salza. However, he heals Goku with a spare bean that Yajirobe gave him earlier. After Krillin and Gohan are beaten down by Salza, Goku appears fully healed. Cooler shows up, holding onto an unconscious Piccolo. He then blasts Piccolo’s body with an unexpected attack as Goku watches in horror. Goku blasts Salza into the distance, and begins to fight Cooler.
After Goku proves to be a worthy opponent, Cooler tells of his history with Frieza. He then reveals his final transformation, one that Frieza never showed or achieved (note that Frieza’s final form patched with robotic parts, shown in the series before he is killed by Future Trunks, is not a transformation), and this one is far more powerful. With it Cooler pummels Goku around effortlessly, despite Goku using the Kaioken attack numerous times. Cooler then proceeds to destroy the landscape. However, after seeing a bird die from wounds inflicted by damage caused during the struggle, Goku thinks back on his friends and family, and how they all would be killed if he let Cooler kill him. He then picks up the dead bird, letting out a yell so powerful it cracks solid stone. Goku then transforms into his Super Saiyan form, and gives enough of his energy to revive the bird. Cooler then finds himself, like Frieza was, grossly outclassed. After attempting to punch and blast the Super Saiyan with no effect, Cooler summons a trump card when he powers up an enormous ball of energy. Cooler launches the attack with hopes to destroy Goku and the Earth along with him. After a stint of struggling, Goku eventually manages to send it back with the Kamehameha wave, forcing Cooler off the Earth, towards the sun. As he hits the sun’s surface, Cooler finally realizes that Goku was none other than the baby Saiyan within the escape pod that he ignored back during Frieza’s attack on Planet Vegeta. Lamenting his naivete, Cooler’s body is then seemingly disintegrated by the sun.
Goku, drained after his battle, is found by Krillin and Gohan. They are looking for Piccolo when Salza reappears and prepares to kill them all. However, before he can attack, he is killed by Piccolo’s “Special Beam Cannon” from a distance. Gohan looks around for Piccolo, and the movie ends with Piccolo gazing skyward.