New challengers Surge and Kit were designed for a single purpose: to replace Sonic and Tails as the world's greatest heroes! And that means it's not just the Blue Blur and his friends who should be wary--Dr. Eggman better watch out too! But has Dr. Starline gone too far this time? Will his master plan succeed, or will these imposters prove impossible to control? One thing's for sure: Surge and Kit mean to make a splash, and Sonic's world will never be the same!