I've had this on my wishlist for years, and my husband was kind enough to give it to me for my birthday. I've spent the past 2 days completely lost in it. I'm surprised it's not more popular, but maybe it was when it was first printed in 1978.
The story is basically about a grandmother and granddaughter who switch places in body and time when they look into a mirror that each of them received on their wedding days in different times. At this point, the story moves chronologically from past to present through the generations who were connected to the mirror in the same "Gingerbread House".
Imagine suddenly finding yourself (a girl from 1978) in an arranged marriage and carried off into the Colorado hills to live in a tiny cabin with no electricity or running water. Or imagine being a girl from the turn of the century and suddenly finding yourself wearing bluejeans and drinking a margarita at a disco with people making out all around you. And then imagine that you don't know the rules of the world you've found yourself in (how to start a wood stove or answer a telephone) and everyone thinks you're going crazy.
It's a simple story, but it's written in a way that drew me in. It's not a time travel story I'll soon forget. It's an instant favorite.