Sonic now residing at Tom and Maddie’s house, was given an opportunity to look after the house while Tom and Maddie go on vacation. At first Sonic found this to be a great way to do the things that Tom would frown upon, only to eventually learn that an old enemy has returned in Green Hills. That enemy is the previously banished Dr. Robotnik who has escaped from the mushroom planet. This time around, he’s accompanied with a red echidna named Knuckles, who blames Sonic for the demise of his echidna tribe. The unlikely duo both share the same goal which is to locate the Master Emerald, a legendary emerald that has the ability to build or destroy civilizations. It’s up to Sonic to prevent Robotnik from obtaining the emerald, and this time he has gained a new friend named Miles “Tails” Prower who has a knack for technology and the ability to use his two tails to make himself fly in the air.