The world has fallen to the Metal Virus, a manufactured plague that transforms all it infects into robotic zombies at Dr. Eggman's command. Even Sonic the Hedgehog has been infected, though his speed has allowed him to keep the virus at bay. Now, with the population more infected than not and the virus constantly spreading, Sonic and his friends in the Restoration launch a desperate plan to cure the world: Tails will synthesize an antidote, Amy will coordinate rescue operations, and Sonic will provide valuable data on how to combat the disease... but when things go awry, it all comes down to the last minute!