Marlo Thomas did a lot of research for her role in Sunday's (8 p.m., Ch. 4) "Held Hostage: The Sis and Jerry Levin Story."

She plays Sis Levin, whose husband (David Dukes) - CNN's Beirut bureau chief - was kidnapped by extremists in 1984. As Jerry's captivity dragged on, Sis became an outspoken activist for peace, making contacts with anyone she thought could help free the hostages.Thomas read all she could on the subject. She talked to the people involved and spent quite a bit of time with Sis Levin herself - even copying her accent for the movie.

But what she didn't expect was to learn first-hand what it meant to be afraid for your safety.

Thomas and the rest of the cast and crew traveled to Israel last fall to film "Held Hostage." And just two weeks into the shoot Iraq invaded Kuwait, upsetting the entire region.

"It was really terrifying," Thomas said. "Two (members) of the American crew went home. We all had a meeting to decide what we should do. We decided we'd run to the airport at the first sign of anything."

Overnight, Israel became a different place. "On the front page of the papers every day there was a picture of a gas mask and where you could pick one up," she said.

"After the invasion, we could see English and American and French ships coming on the horizon. And helicopters overhead all the time - big, huge ones the size of a bus.

"Even weeks after I came home, I'd jump at the sound of a helicopter flying over."

Still, Thomas said the scare helped her understand the trauma Sis Levin went through. "It gave us the feeling of what these people must live with all the time," she said. "It made us as Americans understand better what they live with.

"I was very impressed with how brave Sis was," Thomas said. "I can't imagine anything more terrible than having a member of your family kidnapped."

On the advice of the U.S. State Department, Sis kept quiet for seven months after Jerry's abduction. But increasingly frustrated with American refusal to make real attempts to free the hostages, she became outspoken, appearing on television and making whatever contacts she could -

including contacts with Syrian President Haffaz al-Assad.

"There's nothing in her background that could suggest she'd be that kind of an activist," Thomas said. "She finally said, `We've got to do something. I'm afraid the silence will kill him.'

Sis was criticized in some quarters for making overtures to terrorists who expressed hatred for the United States.

"But she maintained you have to talk peace to your enemies. There's no sense talking peace to your friends," Thomas said.