Bergman's comic masterpiece opens with middle-aged lawyer Frederik Egerman (Gunnar Bjornstrand) again failing to consummate his marriage with the much younger Anne (Ulla Jacobsson).
While visiting a former lover, actress Desiree Armfeldt (Eva Dahlbeck), he crosses swords with her current lover, Count Malcolm (Jarl Kulle), after both men learn that Frederik is the father of her illegitimate child.
At Desiree's behest, her mother invites Egerman, the Count, and their wives along with Egerman's grown son, Henrik (Björn Bjelvenstam) to her manor house for the weekend.
Before their departure, divinity student Henrik wards off the eager advances of the housemaid by reading from the Bible aloud, but it seems clear that he and Anne are quite taken with one another. After arriving at the Ryarp estate the guests are served a dinner spiked with a love potion which provokes swift reactions.
The bewildered Frederik becomes aware of the increasingly intense bond between Henrik and Anne, and the Countess (Margit Carlquist) makes a public bet with her husband that she can seduce Frederik. Shocked by the dinner-table conversation, the strait-laced Henrik retires to his room to commit suicide.
In the course of his bumbling attempt, he has the good fortune to learn why so many prefer sex to death.