My stories are often better termed A character in search of a story." ;-) If you're great at coming up with characters, but their stories lack something -- like a point, a focus, an ending -- and your response is to ... add more characters to explore, these books might be helpful. :-)
Reading writing books on the Kindle is apparently what I'd always wanted to do even before the Kindle was invented :-) I love highlighting and taking notes. I've been carrying around 25 (and growing) writing books to cafes, Europe, the bathroom, even bathrooms in Europe. (Quite often the prices will be or go on sale for just a few dollars.) So I've linked the Kindle version when available. Amazon handily links the other versions on that page.
Blockbuster Plots: Pure & Simple by Martha Alderson. Her system to create an overview of your book to hang on the wall with the Scene Tracker and the Plot Planner looks like a good one. The Scene Tracker charts conflict, emotional development and several other factors for each scene to keep you focused on the elements that create a story. By looking at the chart you'll see when your writing wanders off to explore another interesting character who doesn't move the plot forward.
The strength of this book is in controling your scenes. I enjoy her discussion of theme which makes it more accessible, feeling less like something reserved for literary writers but it isn't the focus. And while she gives a useful overview of creating scenes that flow from action to reaction to action, you'll probably need other books to help you create the scenes.
More to come as I go through the books again, but these two in particular helped me to understand plot and story more. And they're both easy reads. :-)
Save the Cat by Blake Snyder. This is the guy who got it when people scratched their heads at beginnings described as introductions, middles as rising action and endings as falling action. While he wrote about screenplays, his breakdown of each Act into 40 discrete steps that develop both plot and character is very useful for novelists too. He's sold me on the idea that if you can't come up with a log line then you don't have a story. He has simple and expanded templates for log lines.
(Also Save the Cat!® Strikes Back expands on some of the ideas that proved to confuse people in the workshops he gave. And Save the Cat Goes to the Movies breaks down 50 movies with the Save the Cat beat sheet showing that even literary works have a flow. If you like that, Tim Stout has used the Save the Cat beat sheet to dissect 10 graphic novels in Short Notes on Long Comics: 10 Great Examples of Story Structure in Graphic Novels. (Only 99 cents.)
My Story Can Beat Up Your Story: Ten Ways to Toughen Up Your Screenplay from Opening Hook to Knockout Punch by Jeffrey Schechter. Both Snyder and Schechter make The Hero's Journey idea more accessible and understandable for stories that aren't about classic heroes on journeys.
I particularly liked the pattern he describes of how pairs of secondary characters are organized around a like and opposing quality, for instance they will either support the old beliefs the Lead clings to or the new beliefs the Lead is growing towards. I realized that I had naturally pushed the characters in a story I had been writing exactly in those directions to give them different voices. (Only $3.99 currently for the Kindle.)
(There was a chapter he meant to include between 8 and 9. You can download it here.)