A long, long time ago (as the song says), I posted about one page summaries. What I said then is still true now.
A one page summary, or book synopsis, is a one page third person short story of your novel. It's one of those few times that you can tell a story without a single scene, and obviously since you have one single-spaced page, in as few words as possible. Your summary tells the entire plot and subplots of your novel, introduces all major and possibly a few minor characters, and introduces the major thematic elements. Like your one paragraph summary in your cover letter, it also needs to be illustrative of your writing voice and give the editor/agent a sense of how the manuscript will read. Not quite as difficult as a one paragraph summary (because you have more words), these can still be hard to write. It can be hard to figure out what is important enough for the summary. I find that the easiest way to write one of these is to make an outline of your novel with all the major plot markers listed. Then you'll know what you have to include, and you can make choices from there.
More than any other part of a book proposal, the one page summary is where you really get to know your manuscript, where you can really evaluate what does and does not need to be in your novel. Do you find you have 12 subplots and can't fit them into the summary? Then it might be time to reevaluate the necessity of all those twists and turns.
For the rest of the week, we're going to practice the one page summary. Since Facebook did not have as sophisticated of a discussion board as I had expected, I have set up a new forum over at ProBoards: The Buried in the Slush Pile Forum. It's not as pretty as the Ning forum was, but this one is free, and Ning no longer is. I know. Bummer.
I have already started the one page summary board. All you have to do is start a new thread in that group, and then paste your summary in. (Don't worry about the character count. You get 60,000 characters which is roughly 32 double spaced pages. You are aiming for around 500 words which is around 5000 characters.) To leave feedback, just reply to that particular thread. This way no one who wants to participate will be overlooked. (I missed one yesterday, and even once I knew about it, I still had trouble finding it. Hence the switch in forums.) As always, general rules of critique etiquette apply, and on this forum, I have the power to remove comments and ban members for bad behavior. This has never, ever been a problem in the past, but I will exercise that right if necessary.
Finally, a note for the picture book authors: I'm sure you noticed that I kept referring to a one page summary of a novel. Obviously trying to write a one page summary for a picture book would just be silly. However, you can still participate if you like. Feel free to use this time to perfect your one paragraph summary, and then take the additional space on your page to really explore your characters and get to know them -- their motivations, their wants, needs, etc. Granted, very little of that will actually make it into your manuscript text, but it will help you to know these things. For example using Becky's Don Quixote picture book wip, if the little boy's main motivation is to get Mommy's attention, then learning this would help Becky decide if the activities he participates in are helping him try to achieve that goal or if they are just silly for silly's sake. When you're done, feel free to post your paragraphs (and maybe a sentence or two about what you've learned if you like) on the forum. Just be sure to prominently feature Picture Book Practice at the top so we won't be trying to figure out how to rework your unrelated paragraphs into a cohesive summary.