The story started in the post-credit scene of the previous Hedgehog movie continues. Tails searches for Sonic all over Green Hills. Once he finds it, he brings up to date on everything that has happened in Mobius during the time that Sonic has lived in Green Hills to Sonic, Tom and Maddie. He tells them that a great threat is terrorizing Mobius and that they have already faced it. It is about Robotnik, now calling himself Dr. Eggman threatens Mobius with robots and that one of them is a replica of Sonic (Metal Sonic). Our heroes target mobius through a ring. Once there, new characters are introduced (Amy Rose, Knuckels, Shadow and Big). They find Eggman getting clues and engage him in another epic battle.
