Judging by the opening montage of Mrs. Harris, you might prepare yourself for an exercise in high camp. It would be a reasonable assumption. As the credits roll, a parade of black-and-white clips from Mildred Pierce, Sunset Boulevard and other great movies of yesteryear present tough-as-nails dames shooting dead the men who've done 'em wrong.

A fair amount of postmodern irony is in the mix here, but director-writer Phyllis Nagy aspires for much more than campy cool. Like another made-for HBO flick, 2004's The Life and Death of Peter Sellers, Mrs. Harris dabbles in a handful of genres. In this instance, the ripped-from-the-headlines story concerning the slaying of "Scarsdale Diet" guru Dr. Herman Tarnower provides an opportunity to mine lurid docudrama, black comedy and courtroom thriller. Although first-time director Nagy doesn't quite find her groove, she strikes enough right notes to make a compelling story.

We already know it makes for good news copy, of course. When Tarnower was shot to death on March 10, 1980, by his longtime lover, Jean Harris, tabloids across the nation found the crime to be irresistible fodder. The victim, a renowned New York cardiologist, had already become a household name on the strength of a bestselling diet book. The suspect was a prim, respectable headmistress of an elite Virginia girls' school. People ate it up, especially in a lengthy trial that eventually found Harris guilty of second-degree murder.

The movie unfolds with the ill-fated night in which a depressed, gun-wielding Jean Harris (Annette Bening) showed up at the doctor's Westchester County, N.Y., estate, only to discover another woman's lingerie in the bathroom. What transpired next is open to question. Harris claimed she had driven from Virginia to New York with the intention of taking her own life, but that Tarnower (Ben Kingsley) was shot in an ensuing struggle for the gun. Prosecutors countered that Harris killed Tarnower because he had been seeing a younger woman, his assistant Lynn Tryforos (Chloe Sevigny).

Loosely adapted from Shana Alexander's 1983 nonfiction book, "Very Much a Lady," the film intercuts between the murder, the subsequent trial and the years of Harris and Tarnower's tumultuous romance.

It was a relationship steeped in codependency long before the term became the stuff of Oprah shows and self-help books. Herman Tarnower might be "no oil painting," as one character puts it, but he is aggressive and confident, an avid hunter whose prey is equally helpless whether they're on the African plains or in the bedroom. Jean, a divorcee with two young sons, meets him at a dinner party in 1966 and is immediately smitten.

Although she claims later that the two never fought "except over the use of the subjunctive," the on-again, off-again love affair is a textbook case of dysfunction. The doctor, a confirmed bachelor, is selfish, arrogant and tactless. And Jean Harris loves him precisely for the same qualities that cause her so much heartache. As she tells a friend, "Cruelty isn't a crime. Boredom is."

Driving Mrs. Harris are the captivating performances of Bening and Kingsley, both of whom admirably balance poignancy with dark comedy. They demonstrate their considerable acting chops when Jean and Tarnower sleep together for the first time. With the womanizing doctor barking out his commands ("Take off your clothes," "Now make me hard") as if he were instructing a patient to cough, the scene encapsulates the masochism and weird humor that would distinguish their 14-year relationship. The cast boasts some other talented actors -- including Sevigny, Frances Fisher, Frank Whaley and the always impressive Cloris Leachman -- but the film wholly belongs to Bening and Kingsley. Ellen Burstyn, who portrayed Jean Harris in a cheapo made-for-TV movie back in '81, appears in a blink-or-you'll-miss-it cameo as one of Tarnower's ex-conquests.

Mrs. Harris isn't a complete success. Its periodic changes in tone can be a bit jarring, and Nagy's script gives us no sense of who Jean Harris was before she fell under Tarnower's spell. But the movie has energy and panache, and it reveals a surprising amount of tenderness for its sad, troubled protagonist.

Presented in anamorphic widescreen 1.78:1, the DVD is a solid and clean transfer. The picture quality is detailed, with realistic skin tones and fine use of color.

Unremarkable but serviceable, the English track for Mrs. Harris is in Dolby Digital 5.1, with a Spanish dub in Dolby Digital 2.0. Subtitles are available in English, Spanish and French.

The DVD boasts two commentaries. The track with writer-director Phyllis Nagy is by far the more informative of the two. Despite too many stretches of silence, her observations and anecdotes are interesting and provide a fuller appreciation of the seemingly innocuous decisions that go into filmmaking.

Less successful is a commentary featuring Bening and Kingsley. Bening obviously feels close to the movie, but her enthusiasm doesn't always translate into insight. Kingsley, for his part, is relegated to playing Ed McMahon to Bening's Johnny Carson, offering a few "yes, yes, that's right" comments when he finally decides to talk. There is a disappointing lack of rapport between the actors.

Mrs. Harris for the Record: Firsthand Accounts is an intriguing featurette with clips of the real-life principals in the 1980 murder case, including a defense attorney, a prosecutor, the presiding judge and -- best of all -- Harris herself. The only downside is it wraps up after only four minutes and 30 seconds.

By all rights, Mrs. Harris should be cheesy and inadvertently hilarious. Instead, it is often compelling and consistently watchable, a testament to clever filmmaking and two strong lead performances. All in all, the picture is another artistic triumph for HBO.