Dr. Eggman (AKA Dr. Robotnik) is back to continue his zealous search for the Chaos Emeralds needed to fuel his new Death Egg contraption. Now Sonic must thwart the doctor's plans at all costs, but this time he isn't alone as a peculiar two-tailed fox named Miles Prower (AKA Tails) decides to aid him in the battle. Together they must locate the Chaos Emeralds before Dr. Eggman does, and put an end to his diabolical scheme.