Sonic's usual recklessness causes the coveted chaos emeralds to become unstable just as they are about to be activated, resulting in a chaotic explosion that engulfs the area surrounding Dr. Eggman's base. With no way to predict the outcome of the scrambled input, everyone is isolated and stranded. When Sonic finally awakens, he finds himself in an unfamiliar world - an unknown city surrounded by strange people. As he tries to evade the authorities, Sonic stumbles upon the Thorndyke family, who provide him with shelter and protection. Battling against the perception of being a hostile outsider, Sonic resolves to reunite with his friends and find a way back home. Along the way, he must also confront the threat he inadvertently brought to this new world and save it from destruction.