Let me say, first, that it was a FAR better book than Jeffers'. Her level of plagiarism and horrid grammar made me gag for two days straight. This book was far more original, and began with the wedding, leading through to Elizabeth's final discovery that her husband was a vampyre.
What I hated--and I mean hated--was the end. Instead of resolving the problems the book accumulated through some known means, Amanda Grange (the author) pulled a rabbit out of a hat, inventing in the last 20 pages a solution for all of it.
It isn't just this Deus ex Machina I hate. It's any solution slapped on the end of a plot line because the author(s) cannot think of a fix that is integral to the rest of the book. As I write, perhaps I am better at creating the problem and building the tension than I am at finding the solution. Perhaps the solution only comes as I write, and I don't plan for it. However, once the solution has been found, it is my job as a writer to REVISE with that solution in mind. Grange's book's ending tossed all of the suspense and conflict on its head, essentially wiping it out in simple ways with an invented wash cloth of sorts. It's as if she'd written her characters into such a hole that the only way out was some weird prophecy.
The Sherlock Holmes stories had this problem, offering "solutions" to the mysteries only through cryptic details at the last minute, details none of the readers would ever be able to pick up on, but at least some of the clues were there already. I like it best when a plot contains the solutions, yet I miss them, and the ending is a surprise. Then I can re-read and see all the clues I missed the second time around. That, to me, is satisfying.
Now, here is one place this worked for me, and I'll explain why: At the end of Disney's The Little Mermaid, when Triton sees that his daughter loves Prince Eric, he magically gives her the legs she wanted, and she gets to live happily ever after. One could certainly argue that this last-minute "fix" was a deus ex machina. However, Triton could have done the same magic earlier, except for his prejudice against humans and dry land. It takes his near loss of his daughter and personal witness of Prince Eric's bravery to change his mind. You see, the plot isn't really about Ariel's becoming human, but about her father's acceptance of her choice. And that makes his act all the more potent and meaningful, as well as something we could have seen coming (though I was surprised the first time around).
What about all of you? What endings have struck you wrong? When has an ending seemed forced? When has it fundamentally changed what you thought you were reading?