After defeating Dr. Robotnik, Sonic, Tales and Knuckles discover that the evil Shadow has escaped from the military and has begun destroying the city. Now the team must face Shadow, a black hedgehog created by Dr. Robotnik’s grandfather as part of an experiment called Project Shadow. Shadow is searching for the location of the legendary ancient relic of the emerald Flitway, which allows its owner to unlock superpowers. Shadowdaw creates his own robotic version of Sonic, Metal Sonic, which the scientist will use to exact his revenge. A hedgehog named Amy Rose appears through an interdimensional portal to help Sonic and his friends stop their enemies from taking over the world.