In 1950s Iowa City, Iowa, Susan and Scobie eat dinner with their three-year-old son Sammy. Soon their friends, Joey and Clara, stop by to celebrate the Fourth of July. After Sammy goes to sleep, Joey, Clara, and Susan smoke a joint, and everyone dances to music. As they dance, Susan worries that Scobie doesn't love her as much as she loves him. When she catches her husband looking at Clara, she becomes secretly jealous and afraid that he will leave her. As the night goes on, Susan and Scobie discuss whether they will have another child. Scobie wants Sammy to have a sibling, but Susan isn't even sure that she ever wanted to be a mother. Later that night, Susan mentions her jealousy of Clara, who has no children, and accuses Scobie of wanting to sleep with her. Scobie assures his wife that he will not leave her. Susan goes to bed, while Scobie stays up and drinks scotch. In bed, Susan is transported through her memories, from the first time she met Scobie to Sammy's birth. She then wakes up, at first unsure of her location. Soon, Susan realizes that she is at her parents' house with Sammy, and Scobie has left her for Clara.