>> reporter: sally field remembers the moment she won the part of the impossibly innocent tv girl next door, gidget. >> you see people you meet, gidget. >> reporter: but today at 71, field has finally decided to tell the truth of her life offscreen. for every child, the first great mystery is your own family. hers includes a beautiful mother she idolized. >> this giggle, this laughter that, you know, made you laugh even if you didn't want to laugh. >> reporter: a childhood of dark uncertainties, including, she says, abuse at the hand of her step-father. >> sexual child abuse, any child abuse, but sexual child abuse, it -- i think one of the reasons it is, at least, my point of view, it's so damaging is because it's so complicated. there isn't just one feeling. >> reporter: one of the things that we always hear is how early