Richie's plans to party while his parents are out of town are ruined when Fonzie invites the very pregnant wife of one of his oldest friends to stay in Joanie's room and orders Richie to keep an eye on her until her husband returns from a road trip.

Richie's secret scheme to convince sophisticated Cindy Kendall that he has his own apartment by exchanging bedrooms with Fonzie is foiled when her furious father comes looking for her in the middle of the night.