The scene isn't working. Not because the lead actors, Without a Trace star Poppy Montgomery and David Sutcliffe, aren't gelling. They are. But this moment in their Lifetime TV-movie Murder in the Hamptons — airing Monday at 9 pm/ET — needs more juice.

The story, based on actual events, is practically Shakespearean:

Ted Ammon, a fabulously wealthy Manhattan financier, and Generosa Rand, an attractive, demanding real-estate agent, meet cute, marry in 1986, adopt 4-year-old twins from Russia and live like royalty in England and East Hampton, N.Y.

But by the time of this scene, Generosa is pitching fits, paranoid that Ted is having an affair. In 2001, he would be found bludgeoned to death in his bed, and she and her boyfriend, electrician Danny Pelosi (Summerland's Shawn Christian), would be the prime suspects. Two years later, she, too, would be dead — of breast cancer — and in 2004 Pelosi would be convicted of second-degree murder.

In the scene, Generosa is halfway to hysteria. She's supposed to give the kids to Ted (Sutcliffe) for the weekend; instead, she accuses him of attempted kidnapping. Director Jerry Ciccoritti told Montgomery she needed to hit him. "Poppy was like, 'Oh, I don't know if I could do that,'" Sutcliffe recalls. "But as soon as I turned my back, she was just pounding me, boom, boom — and for the subsequent 10 takes." He laughs. "It was what the scene needed. And she went for it."

Montgomery, 30, has a long history of going for what she wants. In her native Sydney, the young Aussie was expelled from six private girls' schools, then dropped out of public school the moment she hit legal age. "Fourteen years, nine months," she says. "I didn't like to conform. I was very outspoken. Like, I thought it was stupid that we had to wear regulation underwear when no one could see it."

At 18, when her own father fired her from a waitressing job, she followed a boyfriend to Florida. "I didn't like the guy, so I got on a Greyhound to L.A.," she says. She's barely stopped working since: In 2001 she played Marilyn Monroe (one of her idols) to great acclaim in the CBS miniseries Blonde; since 2002, she's played FBI agent Samantha Spade in Trace; in Murder, she's in practically every scene. Sutcliffe, Christian and Ciccoritti all use the same words to describe her: focused, intense, committed, fearless. "You can see crazy in the girl — I mean that as a compliment," Christian says.

"I'm so opinionated, that's their polite way of saying no one can get a word in edgewise," Montgomery says. "But I believe in doing things right."

So much so that today, the second-to-last day of shooting, there is palpable tension on the set, with crew members warning one another to stay out of her sight line or else. In the midst of a confrontation scene with Christian, she stalks off the set to take an unscheduled half-hour break in her trailer.

A week after the shoot ends, Montgomery is more relaxed. "Every scene that day was highly emotional," she says. The actress shouted so much that she ended up losing her voice. "That's always good," Montgomery says with a grin.

"Look, I just want to convey the layers of this person. It's so easy to say, 'Generosa equals monster.' But everyone has qualities of bad and good. I don't think anyone's one thing."

Certainly not Poppy Montgomery.