Doug and Carrie Heffernan are a couple whose castle is invaded by Doug's father-in-law, who comes to live with them.

After seeing photos of Carrie's stout mother, Doug worries that Carrie will gain weight as well, and tricks her into starting a diet.

Doug is uneasy when Arthur starts dating Doug's aunt, especially when the relationship becomes intimate--in his basement.

When Doug takes Carrie's dad out for the night, Carrie shows her appreciation in a very amorous way, which leads Doug to spend more time with Arthur.