The inability of Notes on a Scandal to reconcile its camp and collegiate tones is best found in Judi Dench narration where she calls a lunch invitation “a merry flag on the arctic wilderness” of her calendar. She then follows it up with a comment that “lasagna tends to disagree with her bowels.”

The bodily function gag isn’t the only thing dressed up in fancy clothes. Given its Oscar nominations, this tale of two British women’s transgressions and obsessions might seem to be more than a psycho-thriller, maybe a dark look at the murky human rules of infatuation and attraction.

What wins out is a high-class catfight (with a wild, screaming confrontation) between Dench and Cate Blanchett, who work against nagging problems to command the screen in atypical roles.

Barbara (Dench) is the resident biddy at a British high school, a pessimistic chain-smoking history teacher who sees her students as “future plumbers” of the world. In narration that quickly grows unreliable, Barbara puts cruel observations of her surroundings down in journals.

There is much for Barbara to mock in the life of Sheba (Blanchett), a pretty new art teacher. Barbara sees art as an educational waste, expresses shock at the older age of Sheba’s husband (Bill Nighy) and even likens the demeanor of Sheba’s Down Syndrome son to “a court jester.”

Hidden within Barbara’s contempt for Sheba, though, is a passive-aggressive attraction — lesbian on its sexual face, parasitical at its emotional core. Blanchett brings out the exploitable traits in Sheba, plagued by a fireless love life and a complex over how her beauty empowers and limits her.

When Barbara catches Sheba having sex with a 15-year-old student (Andrew Simpson), she views it less as a crime or even an ethical breach, but as a betrayal of chemistry. With emotional blackmail, Barbara baits Sheba with the secret and a hope she’ll will Sheba to something more.

Clocking in at 91 minutes, Scandal is a concerto of destruction and its one strongly hit note is a portrayal of Barbara’s loathsomeness and isolation decaying her soul. Dench’s unsettling confusion of delusion for life is akin to Matt Damon in The Talented Mr. Ripley, without homicidal ideas.

The movie still makes Barbara an unstoppable emotional boogeyman, though, as her consumptive “courtship” renders Scandal a mental slasher movie. Philip Glass’s score grows as intrusive as Barbara’s character, and this coda provides the highpoint of Patrick Marber’s (Closer) superbly snide verbal remarks and exchanges. But the literary pretenses really just serve as a mask.

Scandal essentially is an 80-minute buildup to a throwdown between two Oscar-winning actresses without any real sense of the mental toll of all the leverage and lust thrown around.