What a logline has to carry

A logline is one sentence that has to carry three things: a character who wants something, what stands in the way, and what happens if they fail.

The setup-only version is the common one. "A detective investigates a murder in a small town" names a person and a situation, and nothing else. It does not say what the detective wants beyond doing the job, what makes the town a problem rather than a backdrop, or what it costs him to get it wrong. A reader hears the sentence and keeps waiting for the rest, because the sentence never finished.

The three parts come from three places you already have. The want is the same want the character sheet carries: the field that asks what the character wants is the field the logline borrows from, and the sheet post argues why the two fields want and need stay apart. The obstacle is a person, a place, a rule or a clock, specific enough to picture. "Against the odds" is not an obstacle; the odds are whatever the writer did not think through. The stakes are what failure costs, and they are the part most often left out, because the stakes live in the ending rather than in the premise. A want without a cost is a premise, and a premise is not something you can pitch for long.

The hard part is that the three pull against each other. Make the stakes bigger and the obstacle turns generic. Make the obstacle specific and the want can look small. Most loglines need a few rewrites, and each rewrite is the argument in miniature: what does this person want, what will it cost, who says no.

Beatstack keeps a logline field at the top of every project, next to the target page count. Its job on the board is practical. Every sequence should be describable as a step toward the sentence, and when a sequence resists that description, the board has found the gap while it is still cheap to fix. That is the same check the second act post argues for, a plan that runs out of promises, run here at the size of one sentence instead of one act.

So write the sentence early, and expect to rewrite it. When the film stops matching the sentence, one of them has moved on. Usually it is the sentence, and rewriting it is the cheapest check you own.