It isn't a biological weapon that arrives on the doorstep of Georges and Anne Laurent (French superstars Daniel Auteuil and Juliette Binoche), but a videotape, seemingly filmed from a static camera just outside their house a camera that, judging by the footage, Georges walked right past without noticing. The tape itself isn't that intimidating. But then another one comes, wrapped in what appears to be a child's drawing of someone spitting up blood. Anonymous phone calls are received, and Georges and Anne's twelve-year-old son, Pierrot (Lester Makedonsky), gets a similar blood-spitting drawing delivered to him at school. Subsequent videotapes showcase Georges' childhood home, then a totally new location.
A very similar setup was used in David Lynch's Lost Highway, also featuring a character with the last name Laurent. But Haneke's agenda is more straightforward. Lynch used the device as a gateway into a surreal world, where it served as a metaphor for jealousy. Haneke's world obeys the standard laws of nature, but he rather brilliantly keeps the audience as on edge as his characters are, in the way he integrates the tape footage into the film. We can be watching a scene that seems to be Georges' point of view, then suddenly have the familiar fast-forward or rewind bars show up to make us realize that we've actually been watching the footage on the anonymous tapes. It's a simple trick, but a vaguely disorienting one to keep us unsure.
The real threat, of course, is not what's actually on the tapes, but what might be behind them, and the way that paranoia about such things can drive a wedge between family members, setting them off on each other. If you want to read a metaphor in there about the way terrorism seems to polarize political sides against each other like never before, feel free.
There actually is a potential Arab-phobia connection, but not one based in today's Mid-East issues a key character from Georges' past has been traumatized by a 1961 incident in which French police killed a large group of Algerian protesters. Georges is convinced that this is the man out to get him, but we're not so sure. For one thing, he's the only obvious suspect, which seems reason enough for him not to be the true culprit.
Those expecting a definitive answer on that subject, however, might want to rethink expectations, as the film remains ambiguous. Some critical colleagues have mentioned that if one sits through the end credits, there is a crucial, subtle clue in the very last frame. I missed it, but a theater employee confirmed that he saw it, and mentioned that the viewer should look in the lower left hand area of the screen. Assuming this is all true, it does support the conclusion I was leaning toward anyway. But some viewers prefer more definite solutions.
Caché is one of those rare movies that proves that less can indeed be more, if the writer-director knows what he's doing. The story mostly consists of very simple interior shots in a handful of locations, with no musical score, very minimal sound design, and one very basic special effect, if you can call it that. But it isn't lacking in the slightest, and it arguably achieves a greater creepiness than a story with, say, dungeons and boogeymen would.
To say more about why the film works would be to risk revealing too much. Not knowing is what makes people afraid, and not knowing where Haneke is going is a large part of what works. It isn't your typical scary movie there are no "boo!" moments but it may gradually creep you out, and perhaps even more after you've seen it.