Sonic and Shadow didn't know how they ended up in the world of Equestria, but they persevered and found a way to live in the small town of Ponyville, and they decided to stay for good. However, they get a call from Princess Celestia and Princess Luna who are in dire need of their help, offering a promise of anything they ever dreamed as a reward. And so the two hedgehogs set out on a journey to the unknown, not because of the reward they were being offered, but because their faith in each other and the power of friendship is strong enough that they know they can accomplish anything.