The Laurent family is being terrorized in their own home. Not with bombs, or prank phone calls, or even flaming bags of dogshit on their doorstep—but with a fiendish brand of terror so insidious that, at first glance, it doesn't seem scary at all. Someone is sending them videotapes of their own house—hours and hours of still footage featuring nothing more than the occasional passing car.
After a while, the videos start getting creepier and more personal, and soon they're accompanied by bizarre, childish drawings. Georges (Daniel Auteuil) begins to suspect that the tapes are being sent by a childhood enemy—when he was young he did a very mean thing to an Algerian boy, and he thinks the tapes might be a long-overdue revenge. Naturally, he's too ashamed to tell his wife, Anne (Juliette Binoche), about the asshole thing he did when he was nine, so he alienates her with his secrecy, becoming increasingly erratic and distant as he tries to solve the mystery.
Binoche and Auteuil turn in solid performances as a middle-class couple whose seemingly stable life is slowly falling apart. Caché hinges on the idea that just underneath society, and deep within the lives of normal people, all sorts of vile and unspeakable things lurk in wait—and the two veteran French actors reveal masterful control as they slowly become aware of how unstable their lives really are.
Caché is, in fact, almost too nuanced to be the thriller it purports to be—in addition to the marital drama, it touches on class, voyeurism, childrearing, and some pretty heavy race-related subtext. And it certainly is unconventional, from the bevy of non-thrilling topics it covers to the abrupt, inconclusive ending. But while the film may fail to keep you on the edge of your seat, some of those non-thrilling topics are really pretty interesting: the depiction of a marriage slowly disintegrating, the things done as a child that can make one question their character as an adult, the difficult relationship France has always had, and continues to have, with its non-white citizens... Nope, not a hardcore thriller. But totally worth watching all the same.