It's Valentine's Day and Nergal, the fiend living in Earth's core, appears in Billy's house to court Billy's spinster aunt, Sis. Then, Billy tries ruining Nergal's date, to avoid becoming his nephew. Although initially Sis doesn't show interest in Nergal, she changes her mind when Nergal is stung by bees and she sees his "dance moves". Then, aunt Sis accepts Nergal's marriage proposal, and accompanies him back to the center of the Earth.