Secret of the Black Pearl Thundarr the Barbarian : Season 1 Episode 1

Thundarr, Princess Ariel, and Ookla escort a man who is carrying a magical black pearl that can defend against the two-faced wizard Gemini and his Groundlings (a race of mutated rat people). The man needs the pearl to protect the inhabitants of the village of "Manhat", which is actually the ruins of Manhattan.