After so many battles, the unimaginable has happened as Dr. Eggman defeats Sonic the Hedgehog and conquers the world! With the aid of his newest "creation", a being wielding the power of the mysterious Phantom Ruby, Eggman wastes no time in bringing the citizens of the world to their knees. With Sonic defeated, a ragtag resistance is formed led by Knuckles the Echidna, and soon an unlikely young recruit steps up to hopefully become the new hero the world desperately needs...