Robotnik's revenge: Path of the Dark

After nearly becoming a successful evil scientist, Dr. Eggman proves he is actually a threat. G.U.N. ensures he is permanently put behind bars, under their watch. Thus, the warfare between Sonic and Eggman ceases, and peace is restored.
However, the very thing that keeps the universe together is threatening to fall apart. An unimaginable power is at hand and so is an evil seeking to use it to conquer and devour everything. Can the blue blur and his friends stop this formidable evil in time or will they find themselves powerless against it?