The Planet Mobius has been in a state of perpetual peace for a whole year, free from the influence of the evil Doctor "Eggman" Robotnik and his cronies after their defeat on the Little Planet.

However, on this day, Little Planet returns and with it comes a being of immense power.  A black Hedgehog who can transverse space-time in the blink of an eye.  This is Shadow.

Suddenly, Sonic and his allies are overwhelemed by the sudden return of Eggman and Shadow's unprovoked attack on the Chaos Emeralds of Floating Island in a desperate search for the "Perfect Chaos" energy which is said to be contained within the Master Emerald.

What is the secret of the "Perfect Chaos" energy?  Just what is the true nature of Eggman's plans?  What is the mystery of Shadow?  And, more importantly, can Sonic The Hedgehog stop Eggman and his allies from unleashing an unknown power onto Planet Mobius??

The answers await...