Where the term comes from
Merriam-Webster defines a logline as a simple synopsis of a screenplay, film, novel or similar work that is used for pitching or promotion, and dates it to 1982. Wikipedia adds that the term was introduced in 1982 to describe the plot summary line in a television programming guide. It describes a log line as a brief, usually one-sentence summary that states the central conflict and gives an emotional hook, and quotes one source saying it should contain four facts: the main character, what they want, what stands in the way and what is unique about the story.
Blake Snyder's book on screenwriting, as summarised on Wikipedia's page about Save the Cat, starts with the logline and asks for a one- or two-sentence summary that conveys the tone, dilemma, characters and audience. He proposes testing it by pitching it to anyone who will listen and adjusting as you go.
An example
Imogen Thackeray, writing a heist novel, starts with a weak logline: "A story about maps, loyalty and crime in a changing city." It has no character, goal or obstacle. Her second version reads: "When a retired cartographer learns that her last map is being used to rob a bank, she must find the thief before the police arrest her for drawing the route." Now there is a person, a want, a threat and a twist: the map that made her name has become evidence against her. She tests it on a neighbour, who asks immediately whether the cartographer knows the thief. That question is the one her book answers in chapter eleven.
Common mistakes
- Describing the setting or theme without a character who wants anything.
- Listing plot events instead of the central problem.
- Giving the ending away, since the sentence is a hook and not a full summary.
- Using vague words such as "journey", "secrets" or "dangerous" with no specific stake.
- Cramming in three subplots so the one-sentence summary reads as a paragraph.
How to check your manuscript
Write the logline from memory, without looking at your outline. If you cannot do it in one or two sentences, the story may not yet have a clear centre. Then check that the sentence names your lead, the goal, the opposition and the cost of failure. Read it to someone who does not know the book and note what they ask next. For related terms, see protagonist, antagonist, stakes and conflict.
In Musael, the plan board keeps notes on every scene, so you can check whether the scenes under your logline all serve its goal and obstacle.