Writer's Digest Books
This is one of the books in the Elements Of Fiction Writing series put out by Writer's Digest. In it, the writer explains what sorts of things are needed in order to make a good novel or short story, and how to write them.
He talks about character viewpoints, how to chose them, and what not to do. About the different types of story or ending, for example the circular ending or the linear one. About the different patterns a story can take, and much more.
The author not only explains the different aspects of plot, he gives examples. Two of his favorite examples to use are the Star Wars movies and Lord of the Flies. The first I'm familiar with, the second I've never read, but the way he does it the examples still make sense.
I'd like to write a novel or two and I think reading this book has helped. It's certainly strengthened my ideas of what I'll need for a plotline! And, he's done it in a way that's easy to understand, inspiring and fun to read.