Amanda Seyfried, left, stars as Chloe and Julianne Moore is Catherine in Atom Egoyan's erotic thriller Chloe. (E1 Films)

"Is this turning you on?" a woman intones at one point in Chloe, Atom Egoyan's slick, accessible new thriller. Like much of the Canadian auteur's work, this film depicts secrets, lies, psychic distress and sexual obsession — Chloe's principal characters are forced to examine the mysterious workings of their own hearts and loins.

Egoyan's film is at its best when it focuses on the entanglement that develops between Catherine and Chloe, the hooker she hires to spy on her husband.

The movie opens on a comely young prostitute, Chloe (Amanda Seyfried), while she dresses for a date and describes her ability to morph into teacher, daughter or Playboy pinup, depending on her clients' wishes. She plies her trade in Toronto's upscale Yorkville neighbourhood, where Catherine Stewart (Julianne Moore) works as a gynecologist. First glimpsed giving a pelvic exam, Catherine is brisk and businesslike, not exactly oozing passion when she flatly describes an orgasm as "a series of muscle contractions."

Things are equally sterile on the home front, where Catherine glides past the white walls and floor-to-ceiling windows in the modernist dream house she shares with her professor husband, David (Liam Neeson). As her red-ringed eyes attest, there are stresses — notably a sullen teenaged son (Max Thieriot) who's been sneaking his girlfriend into the house for late-night trysts. Catherine's vague dissatisfaction becomes full blown when her husband fails to make an appearance at his birthday party, phoning home with an unconvincing story about missing his flight.

Unable to quell her mounting suspicions that David's been unfaithful, Catherine hires Chloe to approach her husband, test his fidelity and report back with all the tawdry details. As the two women meet to exchange information in a series of chic Toronto bars, it's clear that a complicated bond is being forged, and Catherine's dormant libido is kicking back into gear.

Julianne Moore is the perfect actor to carry this material, and in Chloe's gripping first hour, she wrings all the seriousness she can from an uneven script. When she confides to the call girl, "I love his hands. They used to grab me everywhere. It used to be that way. I used to be younger," it recalls her identity crises in Todd Haynes' Safe and Far From Heaven. Glancing at her own reflection in powder-room mirrors, she suggests a model wife going bonkers from all the upper-class ennui. Whatever else is happening in Chloe, Moore gives great melodrama.

Egoyan's film is at its best when it focuses on the entanglement that develops between Catherine and Chloe. Cinematographer Paul Sarossy uses his lens to zero in on the women's faces, noting the similarities in their speckled green eyes. It's a nice detail, one that suggests a number of possible routes their relationship could take, including a nurturing, mother-daughter angle that's implicit in a scene where Catherine applies a bandage to Chloe's skinned knee.

But Chloe stumbles once things take a turn towards something more risqué. Scenes that are meant to be erotic are staged with the requisite toplessness and shower steam of an episode of Red Shoe Diaries — you can practically hear Chloe's art-house cred swirling down the drain. The hottest thing in Egoyan's film isn't the sex, but the Toronto locations, which serve as a glamorous backdrop throughout. (Viewers looking for inventive new make-out spots are advised to have drinks at Café Diplomatico, then visit the palm room at the Allan Gardens Conservatory, post-haste.)

David (Liam Neeson, left) is suspected of infidelity by his wife, Catherine (Moore), in Chloe. (E1 Films)

Chloe is an update of the 2003 French art film Nathalie, and screenwriter Erin Cressida Wilson displays a flair for exploring the darker side of female desire. But after she's established the juicy David-Chloe-Catherine triangle, she hits a wall and ends up steering things into pulpy, B-movie territory. The choice yields all kinds of red nail polish and vampy fun, but it feels inconsistent with the more serious tone established in the film's first half.

Then there's the truly nutso climax, which borrows plot points (and stilettos) from a string of early '90s thrillers. It's so implausible that the movie never recovers, in spite of Seyfried and Moore's valiant efforts to disguise trash as art. Chloe is not without its pleasures — just be forewarned that nearly all of them are of the guilty variety.

Chloe opens March 26.

Lee Ferguson writes about the arts for CBC News.