The movie draws a contrast between French and English identity--Julie rolls back the tarp covering the swimming pool halfway and dives below the brown leaves on the surface; Sarah goes in only once the gardener has cleaned it--but that's incidental. And though Julie brings an erotic charge to the house, and Sarah does become fascinated with her (there's one shot of Sagnier lying by the edge of the pool with a moth fluttering about her golden hair that could do it for just about anyone), and the plot gets tangly in keeping with Sarah's vocation as a mystery novelist, the emphasis isn't on what we see happening.

In fact, it's one of those mindfuck movies in which you're never sure if what you've seen did happen, but Sarah's character is so strong it doesn't matter. Julie's increasingly disorderly behavior isn't as important as the sight of Sarah spying on her through windows or from her balcony, or rummaging through her bag, then opening a new folder in her laptop to start a manuscript entitled simply "Julie" and transcribing straight from the girl's diary. We're meant to identify with Sarah and yet the movie makes her kind of creepy. She's nasty to that woman on the Underground and the young writer in the publisher's office; she's possessive of a house she doesn't own; her need to control her space and time while she writes shades into moral disapproval of Julie, which Julie properly resents; and even her unselfconsciousness about her habits is off-putting. When she's upset by Julie's shared-kitchen etiquette she goes to the local cafe and gobbles down a dessert, cutting it with her fork as if she hoped to break the plate (and maybe eat that, too), and then at night she sneaks some of the pate Julie has put in the fridge, washing it down with Julie's wine straight from the bottle, which she then refills with tap water.

Sarah has the classic mixture of public repression and secret self-indulgence but what's fascinating is that as she develops an interest in Julie as the subject for a story all the things that are repellent about Sarah come to seem inextricable from how she works. It's psychologically astute, for instance, to show that Sarah's intense concern for her own privacy is not only compatible with her amoral snoopiness (which comes out more and more as Sarah starts pumping Julie for information she can use as a novelist), but that the snoopiness itself is one of the things Sarah's privacy guards. She has to put up some front to disguise her disrespect for personal boundaries, and it has to be a disguise that enables her to keep disrespecting them. Sarah isn't an out-and-out liar; she'll admit to things, but in a way intended to put Julie off balance and get more out of her. Above all Sarah wants to protect her source of material. That's the play in Swimming Pool's mechanism: Sarah snoops among Julie's secrets but by showing her do it the movie gets behind Sarah's own privet hedges. It's not a question of erotic gratification; the movie catches Sarah feeding off Julie as a writer for whom experience really takes place when she starts arranging it in her mind.