Story structure
Logline
A brief, usually one-sentence summary of a book, film or program that states the central conflict and supplies an emotional hook.
A logline is "a brief (usually one-sentence) summary of a television program, film, short film or book," one that "states the central conflict of the story." Beyond plain summary it provides "an emotional 'hook' to stimulate interest," and it "helps content creators simply and easily sell their work in a single sentence" by focusing on what makes the property unique. The article is explicit that it is not a straight summary of the project: it defines the heart of the work and its premise, not the order of its plot.
The novelist meets the logline at every threshold: the pitch, the query letter, the blurb and the serial description are all loglines in different clothes. Writing one before drafting is also a structure test: a story that cannot be reduced to a single sentence containing a conflict worth reading about has its problem upstream of the prose. It compresses the same promise the narrative hook delivers in chapter one; the openings side is covered in how to start a novel.