Sonic and his friends have made a safe if very rough landing on Space Colony Ark, no thanks to Knuckles hijacking the shuttle. Tails reveals a fake Chaos Emerald he created to help reverse the power of the other six Emeralds and makes a bold plan with Sonic to destroy the Eclipse Cannon.
Meanwhile, Knuckles has quickly recovered the shards of the Master Emerald that were lost during the space flight. No sooner has he regained the pieces, he runs into Rouge the Bat. After a brief but fierce battle, Rouge surrenders her shards and Knuckles fully restores the Master Emerald once again.
Realizing that Sonic holds a fake Chaos Emerald, Eggman captures Amy Rose and uses her as bait for an elaborate trap at the research facility. Sonic falls for the trap and is ejected from the colony in an explosive capsule. Thanks to the use of Chaos Control, Sonic escapes the explosion and has to find his way alone to the Eclipse Cannon.
The final showdown begins as Tails battles Eggman, and at the same time Sonic once again encounters Shadow. The fate of planet Earth hangs in the balance!
