The main cast of characters in Sonic 4 Episode III. After Sonic defeats Metal Sonic, Mecha Sonic, Silver Sonic, the Egg Bonder, and Egg Bomber (returning from Sonic 3 & Knuckles but improved), Sonic returns the Master Emerald to Angel Island, lands safely on the surface with Tails, Amy, and Knuckles, and watches Little Planet orbit the starry skies once again. After Sonic and Tails dash through the four main Zones: Hieroglyphic Island, Neon Egg Capital, Rainbow Rush, and Sky Monarchy, and fought Knuckles on Angel Island, Sonic and Tails infiltrate the Death Egg mk.II's exterior to free Little Planet, rescue Amy, and return the Master Emerald. Sonic and Tails set off to retrieve the Master Emerald.
While Sonic and Tails were up in the Death Egg, Eggman sent out robots to take over South Island and rob the Master Emerald. Sonic and Tails arrived back on their home planet only to see robot guards patrolling everywhere and South Island under Eggman's rule. Eggman was holding Amy hostage the entire time. Little Planet was still imprisoned, and Dr. The Death Egg mk.II was powered down, but not destroyed.
