Dr. Eggman (aka Dr. Robotnik) is searching for the Chaos Emeralds to fuel his new Death Egg engine. One afternoon, he launches a full-scale attack on the island where the Chaos Emeralds are buried, imprisoning all of the helpless animals living there and turning them into mindless worker drones.
Fortunately, Sonic is determined to thwart the Doctor's plans at all costs. This time he isn't alone, as Tails decides to aid him in the battle. Together they must locate the Chaos Emeralds before Dr. Eggman does, and put an end to his diabolical scheme!