The Daytrippers plot
"It's a family affair."
Eliza seems happily married to Louis but one morning finds a love letter in his pocket that is not from her. Completely devastated, she drives to her parents' house where everyone tries to analyze the meaning of the letter. Her domineering opinionated mother, her closed-minded, gentle father, her temperamental sister with her pretentious boyfriend: they all have an opinion, but they remain conjectures. Eliza's mother decides there's only one way for them to find out: confront Louis at work about the love letter. In unison they all board the station wagon, bound for New York City.