Notes on a Scandal may star two of the greatest living actresses, thespians who more often play monarchs than molls, but don’t fool yourself—the movie’s trash, not art. But it’s a kind of high trash, a thinking woman’s “beach viewing,” much in the vein of the delightfully lurid 2003 François Ozon film Swimming Pool.

Based on the novel What Was She Thinking?: Notes on a Scandal by the British writer Zoë Heller, Notes stars Judi Dench as Barbara, a high school history teacher, spinster and self-described “battle-axe” who takes a keen interest in Sheba, the beautiful, bohemian new hire (Cate Blanchett) at the school. When Barbara catches the married Sheba in an after-school tryst with one of her 15-year-old students, she first threatens to report her but then realizes the opportunity to insinuate herself into Sheba’s life. The unsuspecting Sheba lets in this wise new confessor, and the wheels are set in motion for a kind of lesbian Fatal Attraction scenario.

The titular “Notes” are Barbara’s diary passages, which narrate the film. Dench dives into her role with fervor, completely embodying the brittle menace that underlies Barbara’s obsession with Sheba while also communicating her quiet, longstanding pain. “People like Sheba think they know what loneliness is,” she says, soaking in a tub and smoking, and at that moment she is so stoically pathetic we almost see her as a victim in her own right. Indeed, the film continually contrasts the fullness of Sheba’s life—loving husband, two kids, plenty of money, beauty, art—with the utter lack of these things in Barbara’s, making Sheba’s mid-life crisis seem a flighty, insignificant concern of the privileged.

Blanchett’s Sheba certainly is no innocent victim. Her intentions are good, which is more than can be said for Barbara, but she has a sort of pretty-headed obliviousness that becomes increasingly frustrating over the course of the film. “Is she a sphinx or merely stupid?” Barbara asks herself early on. Barbara seems to be hoping for the former, perhaps trying to mold her into it under her guidance, but as the film progresses we viewers begin to see that she is mostly the latter.

No one is innocent in this film, and no one gets away with anything. It’s a scenario that’s not surprising coming from screenwriter Patrick Marber (Closer ), who seems to specialize in depicting relationships as a series of power plays and cruel manipulations. By the end of Notes, one has the feeling that everyone’s fate is a little harsher than they deserved, though their downfall is mostly of their own making. In a Greek tragedy, they’d be called tragic heroes, undone by their own tragic flaws, but in Marber’s world there are no heroes and no epiphanies; they are merely punished and humiliated, and then sent back out to sin again.

Notes on a Scandal is now playing at such locations as AMC Lowes Georgetown, Landmark E Street Cinema and Landmark Bethesda Row.