Annette Bening, <EM>Mrs. Harris</EM> Annette Bening, Mrs. Harris

News flash: Annette Bening has once again fallen in love with a charming, wealthy older man who has a reputation for being a bit of a Casanova.

But unlike the story of Bening's real-life romance  her marriage to Warren Beatty has been going strong for nearly 14 years now  there's no happy ending for the character the Oscar-nominated actress plays in HBO's Mrs. Harris (premiering Feb. 25 at 8 pm/ET). Inspired by Shana Alexander's best-selling book Very Much a Lady, the movie explores the sensational 1980 murder scandal involving Jean Harris, the middle-aged headmistress of an exclusive girls' boarding school who shot and killed her longtime lover, world-famous Scarsdale Diet guru Dr. Herman Tarnower (played here by Ben Kingsley).

After years of tolerating the charismatic bachelor's refusal to marry her and his in-your-face philandering, Harris feared she was losing out to a younger woman (Chloe Sevigny). By then drug-addicted and suicidal, she went to his house one night intending to kill herself. Somehow Tarnower was the one who ended up dead. Although Harris maintained that the shooting was an accident, she was convicted of murdering the 69-year-old doctor and was sent to prison for a dozen years.

"It's a terribly sad story, but at the same time fascinating," says Bening. "She was a woman of enormous competence who also seemed to be on this road to self-destruction. Jean Harris isn't easily summed up, and that's where great drama is." The film, adds Kingsley, is "the autopsy of a relationship. It's like a Greek tragedy. There were all these tiny little accidents and seemingly small, mundane decisions that came together to produce a terrible tragedy."

Though the case was a tabloid staple at the time, Bening knew little about Harris and Tarnower before taking on the role. So she prepared by immersing herself in everything from books and articles written about the case to the actual trial transcripts. She also wound up talking to Harris, now 82, whose prison term was commuted by then-New York governor Mario Cuomo in 1992.

"I didn't want to invade her privacy, but she wanted to speak to me," Bening says. "She said very nice things about Tarnower and the way he made her feel  that he was a wonderful dancer and that he made her feel like Ginger Rogers. When you talk to her, it's really hard to believe she wanted to kill him. So it's hard to understand what happened."

It's also hard to understand why two people who seemed to get so little from each other stayed together for so long. "I think that's what's most fascinating to so many people," Bening says. "Most of us have been involved in crazy kinds of relationships that weren't necessarily healthy but, for reasons that are out of our control, were compelling. But there's a boundary we don't cross. Jean went over that boundary and found herself in a nightmare. It's all so bizarre."

Bening's off-screen life, however, is the picture of normalcy  at least as much as the life of a movie star who's married to an even bigger movie star and has four young children (Kathlyn, 14, Ben, 11, Isabel, 9, and Ella, 5) can be considered normal.

"We're just running around trying to keep all the plates in the air like everyone else," says Bening, who's currently starring on stage in Chekhov's The Cherry Orchard in Los Angeles. "Children completely fill your life. But I wouldn't have it any other way. Every once in a while I look around at people who do movies all the time and go from play to play, and I think that would be great. But I really just always wanted kids, and now I have them. I don't think I'd do well in the world only to satisfy my own interests and desires. That would be a pretty boring life for me."