After defeating Frieza, Goku returns to Earth and goes on a camping trip with Gohan and Krillin. Everything is normal until Cooler - Frieza's brother - sends three henchmen after Goku. A long fight ensues between our heroes and Cooler, in which he transforms into the fourth stage of his evolution and has the edge in the fight... until Goku transforms into a Super Saiyan.
Toei Animation, Toei Company