 When Dr. Eggman breaks into the core of a military base in order to find a top secret weapon, he is surprised to find out that the weapon, Shadow, is a hedgehog nearly identical to Sonic. However, his intentions for the Earth are nowhere near what Sonic would have in mind. Shadow starts causing havoc in the city by stealing a chaos emerald, and Sonic ends up being framed by the military for his actions. Now it s up to Sonic and his friends, the mechanical wizard, Tails, and the guardian of the master emerald, Knuckles, to stop Shadow, Dr. Eggman, and the mysterious treasure hunter Rouge the bat from taking over the world. It is up to you to save the world... or destroy it...