Beginning with the flickering image of a French country estate on a hill, the camera cuts to a stream of children zig-zagging through the estate's shrubbery fast into some kind of makeshift treasure hunt. In 10 seconds, Summer Hours has amassed 40 years of familial history. This day is the birthday of Helene (Edith Scob), the mother of three children, and the grandmother to even more. A modern economy has spread Helene's children out around the globe: Adrienne (Juliette Binoche) is in New York, Jeremie (the handsome Jeremie Renier) is in Peking, and Frederic (Charles Berling) still resides in France. Each of the sibling's immediate families and professional responsibilities have shifted their attentions away from their childhood home and rural past. Helene does not resent her children for a relationship that's been reduced to an annual summer visit, but she is lonely, totally aware that her life has been lived.
With subtlety, Assayas surveys the gaps between the three generations of native Parisians in Summer Hours, gaps that, he argues, may be wider than what existed in previous French societies. But Assayas is no snob. He does not mock the pop-culture tastes of an Americanized youth, or the passing casual interests of tourists being guided through museums of French art history. Rather, Assayas is acknowledging change, accepting an oncoming future where France is no longer the harbinger of influence it once was (it is no coincidence that Adrienne works in the United States and Jeremie in China... the two biggest hubs of international business). When Frederic shows his son a valuable painting hanging in his mother's house, the teenager shrugs and explains, "It's from another era". And when Helene unveils her collection of antique tea sets for Adrienne, she disclaims, "I don't want to weigh you down with objects from another era."
The title, "Summer Hours", recalls the plaintive headings Japanese filmmaker Yasujiro Ozu gave to his later-day films that narrowed-in on the widening cultural shifts between generations in post-WWII Japan. Like Assayas does in Summer Hours, Ozu often expressed a sadness for traditions and cultural norms that were on their inevitable way out, but he never showed contempt for a fast-moving and quickly approaching future. However, acceptance does not demand letting go as Frederic, the oldest sibling, does his last-minute best to preserve pieces of the past for his children to cherish. Frederic fitfully obsesses over a decision to sell his mother's two Corot paintings (weighing yourself down with objects from another era indeed), but his regret is countered by the discovery that Helene often used her valuable art furniture pieces for their practicality... such as storage of cleaning products.
It is Summer Hours' magnificent final sequence that brings the movie's sentiments full circle and hints that Assayas' earlier conclusions (or rather, ours) may have been premature. Frederic's children decide to throw a party at their grandmother's house before it's officially sold away. The teenagers behave exactly as we'd expect them to: smoking, blaring loud pop music from iBooks, bouncing basketballs inside the house, slinging around plastic bags of beer and snack food. Sylvie, Frederic's daughter, goes to find her boyfriend by the pond. They take a walk and she shares a memory about her grandmother, a reflection from a point-of-view we've been shut out of up to this point. Sylvie ends her story with, "My grandmother's dead. Her house is gone." That directness is more profound than anything expressed by one of the adults, but it is also quickly swallowed as Sylvie and her boyfriend climb a brick wall and run into the woods like young lovers do. The "summer hours" are these, the times the younger generation are enjoying now, and not the forgotten ones once shared with Helene. Or, maybe it's a continuation of them.