Q. I'm not one of those scurrilous people in a movie theater who loudly announces the plot ending to the entire audience. But what's best for a synopsis in a query letter? Should I include my ingenious plot twist at the end? Or should I provide intrigue so a literary agent will want to read the manuscript?
A. Do the latter. Provide intrigue so a literary agent will want to read more. A query is only designed to deliver the hook - the cool idea (or catch) for an idea that makes your story work. It's not meant to reveal the twist ending or the true killer. A synopsis is a long document that's something different altogether.
And regarding your movie theater demeanor ... your loss.