We turn to jane fonda's adopted daughter, a daughter we didn't know about. Mary williams is telling her story in lo"the last dauger" and finding success on her own. Juju cng sat down with them for a... See More
We turn to jane fonda's adopted daughter, a daughter we didn't know about. Mary williams is telling her story in lo"the last dauger" and finding success on her own. Juju cng sat down with them for a rare interview. Reporter: She's a hollywood legend from an acting dynasty. It seems like we've been mad at each other. I thought we just didn't like each other. I want to be your friend. Reporter: Who won one of her two oscars for coming home. It's very scary for me. Not going to like the fact that I've changed. I have changed. Reporter: She was known for her radical politics and evolved into an exercise guru. Three, four, five, six. Reporter: But if you think you know all there is to know about jane fonda you're wrong. In addition to her two biological children she has another daughter, mary williams. Last time we walked was the first time you walked since surgery. Reporter: Theirs is a complicated mother/daughter relationship. One that began as a friendship. One that mary williams lays out in her new memoir "the last daughter." They met at a summer camp that jane ran with her then husband politician and activist tom hayden. When she showed up at camp you could tell she was a special person and then didn't come back. Reporter: She grew up poor in oakland, california. Her family belonged to the black panthers. Politically active. Such a tough neighborhood eventually began to swallow her up. This is a hugely smart person but she was failing. I said if you bring your grades up by the end of the year and your mother permits you I'll make sure you go to school in santa monica and live with us. I literally felt like I was dying and when I saw that opportunity I ran. I man for it. Reporter: The inner city kid from oakland took the life line and suddenly found herself living in a beautiful home in santa monica, the child of a screen legend, culture shock. I had no idea. I had no idea at the time i would end up married to ted turner and my black daughter would end up sitting at a table in the black plantation, the only plaque person at the table. Mary was a quick study merging her old family values to new ones. She explains how these vastly different worlds were not so dissimilar after all. The black panther, fondas and turners are as different as all can with be but one this in common not shy of acting on their beliefs. All in the spirit of trying to make the world a better place. Reporter: But mary could never shed her tortured past and it was threatening her prese mother/daughter relationship. I was slowly realizes I was alienating myself from people and the person I did it to the person I loved in the whole world world put me in crisis. Don't say that again, I'll tart crying. Isn't that beautiful? Well, you are. Reporter: What makes you emotional about that? Love. I mean, is there anything else that matters in life? Reporter: Mary threw herself into work helping others and worked for the u.N. In morocco and leapt a hand in rural tanzania and helped locate lost boys in the sudan and hiked the appalachian trail and biked across the u.S. And conducted research in apartment arca conquering her fears but running away, running away from the anger she felt from her biological mother and jane was by herself when she went in search of her. It was a wild experience. The three of us went to lunch and me, white, privileged, movie star and this woman who has had a really rough life. She didn't seem to be angry or resentful. She has a good sense of humor. I found out where -- is it an overstatement to say jane fonda saved your life. It is not an overstatement at all. She doesn't know how amazing she has been and what she has done. Reporter: For "good morning america," I'm juju chang in hollywood, california.
This transcript has been automatically generated and may not be 100% accurate.