Sonic the Hedgehog is a video game legend, and thanks to two successful films, he has already become a star of the silver screen. After managing to save the entire planet and his friends from the all-powerful villain Doctor Robotnik (Jim Carey), he could take a permanent vacation. However, that wouldn't allow for a secret government program labeled "Project Shadow" (so old that Robotnik's grandfather was already working on it). It resulted in the creation of Sonic's evil twin, a creature with incredible strength and the ability to teleport. And now this misfit is about to go for the beloved blue hedgehog's throat. When Sonic realizes that Shadow is beyond his powers, he decides to team up with someone he would never normally team up with – Doctor Robotnik – for the greater good.