Evil Cadence(Queen Chrysalis) discovered an abandoned base up in space. She found out it is the Death Egg Mk.II, created by Dr, Eggman. So she uses the base as her lair. She also founded Eggman's Egg Heart which was destroyed by Sonic and Tails and she repaired it with her dark powers, AND HIGHLY ADVANCED!! So Sonic and Tails team up with Dashie and Fluttershy to defeat Chrysalis once and for all, but they have to pass Eggman and Metal Sonic, which they are working for them.