Sonic Underground

Season 1

Episode 29: New Echidna in Town – Chaos Emerald Crisis (Part 3 of 3)

Knuckles bargains with Robotnik in order to recover and repair the Chaos Emerald before Mobius is destroyed but, to acquire the villain's help, the echidna must betray the Hedgehogs. After rescuing his friends from the Roboticizer, Knuckles and the Sonic Underground must now combat Dingo transformed by the chaos energy into a terrifying monster.