Coerced by the voice in his head, Knuckles absorbs a part of the broken Chaos Emerald, transforming into a Kaiju himself. Sonic is freed, at the cost of Knuckles' sanity. In a blind rage, the corrupted Kaiju Knuckles goes on to kill his friends and destroy the village he was sworn to protect, and with the intervention from an alternate Amy and Tails, continue the carnage in other universes.