After another tough battle against the nefarious Dr. Eggman in his new airship fortress, Sonic and Shadow accidentally warp themselves, a friend, and Eggman along with his entire robot army to Equestria.

Now with the Chaos Emeralds scattered around this dimension, Sonic must band together with the former Elements of Harmony to find them before Eggman does.

But the doctor isn't done. With his robot army and a method of rebuilding his fleet still at his disposal along a new ally in his cause, he plots to turn Equestria into his robotic empire as well. So the Blue Blur is on the move to save the world once more.