At a base in the middle of the night, The evil Dr. Eggman took the seven Chaos Emeralds and a hostage. Sonic the Hedgehog, the speedy hero came to save the day, but accidentaly sets off a machine that performs Chaos Control, warping him, his friends, and Eggman, to a world of humans. While on this strange new planet, Sonic and Co. meet a boy named Chris Thorndyke and befriend him as they take on Dr. Eggman to collect the 7 Chaos Emeralds, stop the water-creature Chaos, and save the world from the Ultimate Lifeform.