One day, Knuckles is in Angle Island doing what he does best, guarding the Master Emerald. Mecha Sonic eventually charged towards Knuckles, took the Master Emerald, and left Angle Island. Apparently, this is for Eggman's latest project that can potentially put the entire Angle Island at risk. Knuckles then decided to go to the old Hidden Palace. The entire purpose was to collect the 8 chaos emeralds and 8 chaos rings from different zones to defeat both Mecha Sonic and Dr. Eggman. Once Knuckles defeated Mecha Sonic and Dr. Eggman, Knuckles then returns the Master Emerald back to Angle Island, where he would continue to guard the Master Emerald for a good amount of time.