Sonic the Hedgehog #81
- Publisher: Archie Comics
- Written By: Ken Penders, Karl Bollers
- Art By: Ken Penders, Manny Galan, James Fry, Nelson Ribeiro, Steven Butler, Chris Allan, Andrew Pepoy, Pam Eklund, Harvey Mercad
- Language: English
- Digital Release Date: August 3rd, 2012
The mysteries of the Hidden City of The Ancients continue to obsess the heroes: Are the citizens of this pocket environment hostile or friendly? Could they be the answer to Planet Mobius' secret origin? Will Sonic and the others from Knothole Village be ambassadors of peace or will they be forced to mobilize for conflict? Meanwhile, in the Knuckles story: In pursuit of the evil Dr. Robotnik (who stole shards of the Master Emerald), Knuckles follows him deep into the mysterious Cat Country where he finds the Mystic Ruins. Time is running out as the grounded Floating Island is invaded by Cat People. And in the backup solo story, Amy Rose gets used to her new body... and her new powers?