In the third animated series based on SEGA's character Sonic the Hedgehog, Sonic and his two siblings, Manic and Sonia create the hit rock band, Sonic Underground. But alongside this they are the children of Queen Aleana of Mobius. Queen Aleana was abandoned from by Sonic's enemy, Dr. Robotnik who turned Mobius into a waste land. So now Sonic, Manic and Sonia must continue to battle Dr. Robotnik and his evil sidekicks, with the aid of their metal medallions and bring peace to Mobius and find their mother! Will they defeat Robotnik? The resistance begins on Sonic Underground!