Angelina Jolie: Billy Bob, Knives and Sex

July 11 -- At 28, Angelina Jolie is one of the reigning queens of the red carpet.

Watch Barbara Walters' full report Friday at 10 p.m. on 20/20.

Even before Lara Croft Tomb Raider made her a blockbuster action star, the daughter of Oscar-winning actor Jon Voight had already racked up a number of prestigious awards for her many dramatic roles — including the heroin-addicted, lesbian supermodel Gia.

Three years ago, she took home the top prize of all, an Oscar, for her stunning work as a charming, but dangerously disturbed young woman in Girl, Interrupted.

But for Jolie, the adulation came with an edge. Words like "dark," "weird," even "crazy" began to pop up in connection with the tattooed beauty — and that's just what she said about herself.

Things only got stranger when, at 24, she eloped with then-44-year-old actor and writer Billy Bob Thornton. It was her second marriage, his fifth.

The newlyweds seemed to revel in telling the world about their obsessive love for each other and their quirks. In an ET appearance, for example, Thornton said, "I wear her underwear a lot when we're away. And she wears mine."

Tomb Raider, Cambodia and a Baby Boy

But as Jolie was working on the first Tomb Raider film, set partly in Cambodia, she had no idea then that the movie was about to set her on a brand-new path in life — one that would eventually lead to the end of her seemingly rapturous marriage and the beginning of her life as a mother.

For the film, Jolie spent two weeks on location in Cambodia — a beautiful country with a terrible history of civil war and genocide. Jolie said the experience deeply moved her.

"When we left, I cried for about three days, and I didn't know why," the actress told ABCNEWS' Barbara Walters in an interview airing tonight on 20/20. "I didn't know what that country had gone through, I didn't learn about it in history, and they were so warm, and so beautiful, and so pure and honest, and the country, I just loved the country."

Struck by the poverty she had witnessed, Jolie began traveling the world for the U.N. Refugee Agency as a goodwill ambassador. She went to Africa and Thailand, visiting refugee camps and orphanages. And then, she went back back to Cambodia, where says she made a monumental decision: It was time to adopt a child of her own.

"I've always wanted to adopt. I've always, uh, I don't know whether I was a little kid and I heard about what an orphan was, but I've always felt that I'd find my family across the world," she said.

As happens in all foreign adoptions, Jolie and Thornton had to undergo a U.S. Immigration Service investigation into their fitness as adoptive parents. Jolie admits she was a little nervous about the home visit.

"As an actor you know, you're being evaluated, and then you've got these crazy stories about you, and you're being evaluated whether you can be a parent, and they say that you're nuts," she said.

At the time, one could be forgiven for having a few questions about Mr. and Mrs. Thornton. After all, Rolling Stone magazine had just declared theirs to be America's most dangerous marriage. They famously wore long silver chains with lockets containing each other's blood. They kept a pet rat in a cage in the bedroom. And for their anniversary, Angelina gave Billy Bob a grave plot.