Knuckles' past comes back to haunt him in a big way! The long-lost city of Echidnaopolis makes its ghostly return but at what price to Knuckles' home, the Floating Island? Knuckles is also reunited with his mother and his ancestor Hawking, the oldest living Guardian. But new villains arrive as the Dingo Regime is thrust back into the fray, while the old villains of the Dark Legion and Enerjak return to wreak havoc! All this and the debut of fan-favorite Julie-Su!