I haven't seen this one in decades. Maybe not even since its original run. It's all about the three year old daughter in a wealthy family who is kidnapped. Then 14 years later a teenage girl (Stephanie Zimbalist as Ann) appears on said rich family's doorstep. The circumstantial evidence that says she might be the missing girl is her "mom's" deathbed confession that she was in fact found, and found with a locket that had a picture of the wealthy Talbot family inside. The stepdad brings this to the attention of the police and then to the Talbots with the family matriarch and the missing girl's grandma (Geraldine Fitzgerald) badly wanting this to be the truth. The mother of the missing girl is played by Shirley Jones, now a widow.
Before DNA, all you have is circumstantial evidence. A three year old was not old enough to have dental records, and Ann and the missing girl have the same physical condition - spina bifida. Did I mention Ann is heir to her dead dad's trust if she is ruled the daughter? So while this is all being sorted out, Ann moves into the Talbot home. She has encounters with less than subtle messages that somebody is not thrilled to have her back, if she is indeed back. She also manages to steal away "mom's" tennis instructor lover, played by Patrick Wayne, John Wayne's son. Duke couldn't have been happy about this. The kid is made up to look like someone out of some porn film, even by 70s standards if I remember correctly. But I digress.
I remember the scary scenes having severe thunderstorms for emphasis. But the reason I really remember what seems like a pretty routine coming of age/long lost kid story? The ending is one that is jarring, especially considering this film was made for TV 45 years ago. It was made by Paramount so of course it is inaccessible. If you ever get a chance it is definitely worth a watch based on my decades old memory.