The fastest thing alive returns in an all-new adventure of a lifetime. When the evil Dr. Robotnik returns for revenge with the help of a brawny echidna named Knuckles, Sonic the Hedgehog will have to combine brains and skill with his new hovering buddy Tails the Fox traveling across the planet to stop the mischievous duo from conquering the world with a dangerous emerald holding the potential for maximum devastation.