Notes on a Scandal

“People have always trusted me with their secrets,” says Barbara Covett (Judi Dench) as “Notes on a Scandal” begins. “But who do I trust with mine? You, only you.” And who is her sole confidante? Her diary, of course. Barbara, of all people, knows you’d have to be crazy to trust another human being with secrets.

Based on Zoe Heller’s novel (shortlisted for the 2003 Booker Prize), “Notes on a Scandal” is a breezy and compact melodrama, with a portentous Philip Glass musical score that belies the film’s tabloid-headline juiciness. Affairs, gossip, scandal — there’s nothing too deep going on here, though the letter-perfect performances and the British accents are liable to make you think otherwise.

Barbara is a haughty, sour old spinster who teaches history at a lower-class secondary school in London. She views teaching as nothing more than “crowd control,” refers to another educator as “a pig in knickers,” and looks down her nose at colleagues and students alike. She’s desperately lonely and nakedly manipulative.

What’s fascinating is that even in her diary entries, which we hear through her narration, she makes no attempt to justify herself. She coldly calculates how to force people to be her friends and how to soothe her loneliness with human contact (no matter how awkward). When she learns a secret held by Sheba Hart (Cate Blanchett), the beautiful new art teacher, she tells her diary in no uncertain terms how she’ll use her knowledge to blackmail Sheba into friendship. Why, she’ll be Sheba’s most trusted adviser! Sheba will rely on her for guidance. She’ll have to: It would be a shame if Barbara had to let the secret slip out in public….

Sheba’s secret is that she is having an affair with a 15-year-old student named Steven (Andrew Simpson). There is no particular reason for her to have strayed from her faithful, somewhat older husband (Bill Nighy), with whom she has a teenage daughter and a son with Down Syndrome; the affair has just sort of happened, the way affairs sometimes do. (Note that Patrick Marber, adapted the screenplay, did the same for 2004’s “Closer,” which had similar characters in similarly adulterous situations.) She likes Barbara at first, is soon put off by her cynical elitism, yet realizes she can’t end the friendship without suffering certain consequences.

Richard Eyre (“Stage Beauty,” “Iris”) directs the story at a fiery tempo, and his cast makes the most of the salacious (but discreetly filmed) material. It often has the marks of a psychological thriller, where the viewer is dying to know what will happen to the characters not physically, but emotionally. By using just 92 minutes to tell a story that many films would drag out for 120, Eyre keeps the tension unflaggingly high.

Cate Blanchett’s performance as the conflicted art teacher — she of the chaotic-but-loving household, the starry-eyed idealism about the teaching profession — is wistful and sympathetic, while Bill Nighy can always be relied upon for some dark humor in the film’s margins. Seventeen-year-old newcomer Andrew Simpson, who lives the dream of many adolescent boys by making out with Cate Blanchett, has a surprisingly good turn as Steven, a cocky, emotional wreck.

Of course, the film belongs to Judi Dench, as do most films in which she appears. Barbara is a mesmerizing character to examine, obsessive to the point of being dangerous, self-serving in a way that is over-the-top yet chillingly recognizable. She sets up impossible tests of devotion just so she can be disappointed by her friends’ lack of commitment to her, thus fulfilling her most basic desire: to be miserable.

All the nooks and crannies of Dench’s refreshingly blunt and subtly sociopathic performance make the film a creepy, voyeuristic pleasure. Do not listen to the people who insist the film is brilliant, classy, or groundbreaking, for it is none of those things. It is, however, an awful lot of fun to watch.

B+ (1 hr., 32 min.; R, a handful of harsh profanity, brief strong sexuality.)