He-Man and the Masters of the Universe (1983)

Season 1: Episode 13

Skeletor wants to steal the Widgets' Coridite- a powerful mineral substance, out of which He-Man's harness is made. Evil-Lyn devises a cunning scheme to help him; she disguises herself as a young girl lost in the forest, and persuades the Widgets to let her enter their fortress. She then tricks the Widget guard Squinch into letting her enter the private chamber where the Coridite is kept, then she steals the Coridite and takes it to Skeletor! Skeletor plans to use the Coridite to form himself a new chest plate that will make him as powerful as He-Man- can He-Man stop Skeletor's scheme and retrieve the Coridite before his most dangerous foe becomes as powerful as him?