Once settled in Green Hills, Sonic is eager to prove he has the makings of a true hero. And the heroic challenge is soon upon him: the villainous Dr. Robotnik is once again on the prowl. This time with his mysterious partner Knuckles. Together they search for a priceless emerald, which contains powers that can destroy entire civilizations. Sonic teams up with foxy Tales to embark on a journey around the world to find the emerald before it gets into the wrong hands.