Poisoned by Eggman's new creations, Amy Rose has fallen into a comatose state. Left alone to find the ingredients for an impossible cure, Sonic, Tails and Knuckles must travel through different dimensions and fight against Robotnik's monsters before they run out of time. But the question still remains: how far will the Blue Blur go to save someone he thought he'd never care for?

Using DNA coding from the heroes and the lost magic rings, Eggman has created evil Darkspine clones of Sonic and the others. As the counterparts wreck havoc, Sonic and the others are framed for the actions and are hunted by Mobius' military. With their home starting to crumble and Eggman beginning to rise to power, who will survive the day of the Darkspine, and which side will win?

When a mysterious cat from another dimension comes to eliminate Blaze the Cat, the last known pyrokinetic in the universe, Sonic and the others must face this newcomer. However, after learning that the cat doesn't want to kill Blaze, but has to in order to stay alive, the heroes must hatch a plan to save the icy cat and stop his masters, before they all get frozen over.