The story itself surrounds a mischievous goblin (a small dwarfish man with the head of a cat), and his pestering of “the miller” with whom he finds on his moonlit travels.
Mae'r stori ei hun am goblyn direidus (dyn bach gyda phen cath) sy'n plagio'r melinydd y mae'n dod o hyd iddo ar ei deithiau yng ngolau'r lleuad.