The New Threat.Five years have passed since Goku's victory at the 23rd World Martial Arts Tournament. Goku's son, Gohan, is wandering around the woods outside of his house when a tiger steals his hat. While he's looking for the tiger, he accidentally falls into a river. Goku, searching for his son, finds his hat. He suddenly sees Gohan floating down a river, but he can't reach him in time before he goes over a waterfall. Goku looks up and sees Gohan clinging to a branch, having somehow jumped out of the river. With Gohan safe, they head to Master Roshi's house. Meanwhile, a mysterious alien has arrived on Earth looking for a man named Kakarrot. With a special device: the Scouter he wears on his head, he searches for high power levels on Earth. He finds Piccolo, whose attack is completely ineffective. The alien is about to devastate Piccolo when he finds a higher power level and flies off.