After the defeat of Julian Robotnik, Sonic and his Freedom Fighter friends have finally met Sonic's siblings Sonia and Manic, who have important news about their search for their mother Aleena. But just before they could hear it, Julian's equally cruel and more powerful cousin Ivo Robotnik, who has inherited everything Julian owned, has plans to enact his revenge on what happened to his mentor and cousin. He has shown his merciless wrath by sending his most powerful robots to Angel Island, attacking Knuckles, and shattered the Master Emerald, sinking the island! Now he plans to find the rest of the Chaos Emeralds, one Sonic threw into the ocean, to power an ancient being of extraordinary power dangerous enough to wipe out Sonic and the Freedom Fighters as if they never existed! Will Sonic and his team defeat the new Robotnik and save Mobius, with Knuckles, Sonia and Manic at their side? Or will Ivo finally have his revenge?
