I don't want to say too much about the story and give away the secrets, but this one is definitely one of Diana Wynne Jones' better books. I'd recommend it to anyone who wants a well-written, exciting mystery with a dab of the paranormal and a touch of strange.
From back of the book: Polly has two sets of memories . . . One is normal: school, home, friends. The other, stranger memories begin nine years ago, when she was ten and gate-crashed an odd funeral in the mansion near her grandmother's house. Polly's just beginning to recall the sometimes marvelous, sometimes frightening adventures she embarked on with Tom Lynn after that. And then she did something terrible, and everything changed.
But what did she do? Why can't she remember? Polly must uncover the secret, or her true love--and perhaps Polly herself---will be lost.
At the age of seven, Polly accidentally wanders into a funeral and meets Thomas Lynn, a professional cellist who become intertwined in her life and emotions, both as the father figure that Polly, the child of a broken home, needs - and later - it seems - as the recipient of a teenage crush.
But, as a college student, Polly suddenly comes to the realization that she hasn't thought of Thomas in ages, although he was terribly important to her. And no one she talks to seems to remember him at all. Other things in her memory seem to be evidence of other discrepancies... is she going crazy? Or is something more sinister at work?
Remembering, she uncovers a bizarre network of plots and influence that all seems to center on "That House" where she saw the funeral, and the wealthy and strange family that inhabits it.
This is an ambitious and complicated book, and by far the darkest I've read by Jones, as she brings the Tam Lin legend into 1980's Britain. It's a YA book, but deals with difficult themes such as neglectful parents and relationships with both older men and pushy peers in a tasteful but emotionally unflinching way.
Although it's written in a very subtle way (nothing at all obviously supernatural or occult happens for nearly half the book), it's a tense, compelling read - hard to put down.
However, the end, where Polly finally uncovers the truth, and discovers what she must do, is very confusing - and, from reading other reviews, I'm not the only one to find it so.
We are told that Polly has figured out her course of action from reading about Tam Lin and Thomas the Rhymer, but we aren't told exactly *what* she read, so her strange, logically-backward approach is rather mysterious. The reader just kinda has to say, "Okay, I guess that made sense for some reason.... not sure why!"