Summary Courtesy of The Unofficial Captain N Homepage

King Charles is about to come home through a warp zone that only opens every 1000 video years. But he decides to send a supercomputer called Gameboy in his place. Gameboy turns out to be nothing but trouble for the N Team. Mother Brain gets Gameboy, and Dr. Wily turns him into Game Brain. When the N Team comes to Metroid to rescue Gameboy, Game Brain sends monsters after them. Duke comes to the rescue, pulling the cords out of Gameboy with his teeth! The monsters disappear. Back at the Palace, the gang officially welcomes Gameboy to the N Team.