As a girl, Marcy Heidish loved reading about courageous women. So it was natural, she says, that she grew up to write a book about an energetic, activist woman.

At the suggestion of a friend, she wrote about the 19th-century slave libertor Harriet Tubman. And now her novel, "A Woman Called Moses," has been made into the four-hour television movie that concludes tonight at 9 on Channel 4.

But as a middle-class, Vassar-educated white writing about an illiterate, socially astute black woman, Heidish feared she might be criticized by Afro-American intellectuals.

"I worried about critics," she says, especially following the barrage of criticism by blacks that met William Styron's book, "The Confessions of Nat Turner," after its publication a decade ago.

The Styron book, a fictionalized account of the Virginia slave who led an abortive rebellion against the planter class in 1831, was denounced as among other things a creation of white sexual fantasy. But the Heidish book has received warm praise.

In her first novel, Heidish displays a convincing command of 19th-century Afro-American idioms and thought.

"I think Harriet transcended differences," says the author. "She had so many features that belong to everyone, that underlie the human condition. If I had written a book about Joan of Arc, it would've been different because medieval culture was different. But there're some things that are just common to everyone."

In order to write about a 19th-century personality, Heidish researched Tubman for several months, at the Library of Congress, the Howard University Library and the New York City Library.

"I had a big stack of notebooks on my desk," she says with a laugh. "Before sitting down to write. I went over to the Eastern Shore to walk in places where she (Tubman) had walked."

While Heidish was studying for a master' in theater arts at American University, a friend suggested Tubman as the subject for a play Heidish wanted to write.

"I didn't thing I had any talent as a creative writer, she says, "So I wrote an article about Harriet for Ms. Magazine. Then my agent suggested I write a children's book about Harriet. But the book started in the first person and kept going as an adult book. I guess that's part of the creative proess."

A native of Manhattan, Heidish, 31, lives in Arlington with her husband, James, a commercial artist. She spends much of her time writing in a small upstairs room of their three-bedroom Cape Cod house.

Highly protecitve of her privacy, Heidish has an unlisted phone number and only friends know the correct number of rings that will elicit an annswer.

In conversation with strangers, she backs away timidly. "I covered up my shyness for years with vivaciousness," she says, "but it got to be too much of a burden."

However, there may be a swinging side to Heidish. At a recent screening of the movie based on her novel, she cut a conspicuous figure in black leather pants.

"I don't know why I bought those pants," she says with a laugh. "Maybe I needed to do something different that day."

Heidish is writing away these days on another historical novel -- this time about an early American white woman. But she won't supply any details.

"After I finish it, and it's due in June, I hope to go on to something contemporary," she says.

Whatever comes, Heidish thinks she'll continue writing about the social and political roles of women.

"I think there should be more books on women who believe in a great idea, a grand principle. This would give more role models for women."