Catastrophe looms when K.C. Cunningham reluctantly agrees to go to a costume party with socially inept Melvin Belvin after Marion encourages her shy niece to start dating.

Howard Cunningham dreads his quarrelsome older brother's Christmas visit and little Heather Pfister asks Santa Claus to help her mother, Ashley, make-up with the parents who disinherited her for marrying against their wishes.