The story happens between 29 June and 29 July, presumably in 1970. Intertitles of the dates are displayed before the daily events are shown.
While holidaying at Lake Annecy on the eve of his wedding, career diplomat Jérôme accidentally meets up with Aurora, an old friend. Through Aurora, he meets Aurora's landlady, Madame Walter, and Laura, Madame Walter's youngest teenage daughter. Observant Aurora detects Laura's crush on Jérôme and tells him. After Jérôme and Laura take a hike in the mountains together, she confesses that she is "a little in love with" Jérôme.
Days later (on 8 July), Laura's attractive older step-sister Claire arrives. Upon seeing Claire's knee while she is on a ladder, Jérôme finds himself longing to touch it, but he controls his temptation. Eventually an opportunity presents itself during a boat trip on the lake when Jérôme and Claire have to seek shelter in a hut from an approaching storm. Jérôme tells Claire that he saw her boyfriend, Gilles, together with another girl, Muriel. When Claire starts to cry Jérôme consoles her by placing his hand upon Claire's knee. Jérôme later delightedly tells Aurora that it had taken him great courage to touch Claire's knee and that doing so has exorcised his desire of her from him. Gilles returns and tries to give Claire excuses as to why he was with Muriel.
The film was a huge critical success. On the review aggregator website Rotten Tomatoes, Claire's Knee hold an approval rating of 96%, based on 23 critic reviews with an average rating of 8.3/10. The site's consensus reads: "Told through precise body language and sunny wit, Claire's Knee makes an unusual love story feel universal".[4]
Vincent Canby of The New York Times called it "something close to a perfect film".[5] Cecile Mury of Télérama said: "This camera outdoors gives the appearance of a small story where it goes 'nothing'. Yet these 'fragments of a love speech' make up a special study of desire, verbal pleasure, almost literary, which accompanies every inclination. A jewel".
Style
It was Rohmer's second film shot in color, as he explained: "the presence of the lake and the mountains is stronger in color than in black and white. It is a film I couldn't imagine in black and white. The color green seems to me essential in that film...This film would have no value to me in black and white".[5]