Space Ace/Dexter and his sister Kimberly work for Space Marshall Vaugh to keep the peace in the universe. They fight the evil alien commander Borf and keep him from invading Earth. Again, as with Donkey Kong, Ruby Spears took artistic license with the relationship with Kimberly and Dexter. In the Don Bluth film canon, Kimberly is Ace's girlfriend, not sister. Also, in the video game, Dexter had certain chances to revert to Ace, his full-grown self, whereas in the cartoon the Ace/Dexter phases seemed to happen on their own and at often incovenient times for the hero.