Metal Sonic has been Eggman's prisoner ever since the events of Sonic Heroes, but when he breaks out one and a half years later, all hell is about to break loose. When Sonic realises he can't handle the robot on his own, help comes from an unlikely source

Metared, a new robot Eggman created, has gathered a number of other robots such as Metal Sonic and Mecha Sonic, to one meeting where they discuss new plans every week in order to defeat Sonic the Hedgehog.