Beat sheet
Also: Save the Cat beat sheet
A beat sheet is a one-page outline that maps a story's major turning points — opening image, catalyst, midpoint, all-is-lost, finale — before a word of script is written. The best-known is Blake Snyder's fifteen-beat Save the Cat sheet, which assigns each beat an approximate page in a feature.
A beat sheet lists the load-bearing moments of a story in order, with rough page or percentage targets, so the writer can see the architecture at a glance and find structural holes before drafting.
The Save the Cat beat sheet is the most widely used template — fifteen beats from "Opening Image" to "Final Image." It is a scaffold, not a formula: working writers bend it constantly, but it remains a fast diagnostic for where a story sags.