Fire and Hemlock is a fantasy novel by Diana Wynne Jones. It is generally listed as a young adult novel, but the story follows the main character from the age of nine to 18, making it a bit more wide-ranging than most young adult novels. It is something of a coming-of-age story, and a slightly creepy one at that. It is, more than anything else, written for fans of Diana Wynne Jones, although even among those refined circles it is often seen as a bit of a flop.
The story begins with Polly, about to leave home for college, having the sudden realization that she can remember two alternative pasts, and that she can't tell which one is real. The body of the story is a prolonged 'flashback' of her youth, starting with her ninth year, when she accidentally crashed a funeral and met an interesting man. This man turns out to be a poor relation of the family of the deceased, and is not at all comfortable with his wealthy ex-in-laws, and so is perfectly willing to explore the house with Polly, involve her in a minor art theft, and invent an alternative reality with her. As the years go on, Polly finds that she has become linked to the family through incomprehensible magical means, and that the imaginary world that she created is starting to become more and more real. But at some point this past disappeared, and was replaced by a much more dreary one. And least, she thinks that's what happened.
The parts of the story describing Polly as a younger girl and teenager are quite vivid and amusing, and are very much like Mrs. Jones' other works for children, although perhaps a bit darker, what with Polly's family going through a divorce, her mother having a nervous breakdown, Polly herself having a sinister stalker or two, and reality shifting in unpleasant ways. This is offset by Polly's exciting adventures, good friends, and the emergence of her rather unexpected and unexplained magical ability -- if that's what it is.
At the end of the book the story runs into two major problems; one is that the magic is not explained very well, making the final solution to everyone's problems something of a confusing mystery. The other is a bit of a spoiler, so is hidden in the pipelink. The story also ends rather abruptly, although this is a minor sin that can be easily forgotten.
Fire and Hemlock is somewhat akin in scope and quality to Diana Wynne Jones' book The Time of the Ghost, although I think that Fire and Hemlock is the better of the two. In my opinion, the core story in this book is as good as anything that Diana Wynne Jones has written, but the intro and, especially, the conclusion are disappointing. This has the unfortunate effect of leaving the reader with the feeling that they have read a rather dull book, which is not actually true. As such, I recommend that any fan read it, but that they be mentally prepared to enjoy the good bits even while being disappointed with parts of the story.