Refers to the constructed sequence of events in a story, novel, film, or play. Often used when discussing narrative structure.
この小説は筋立てがしっかりしている。
This novel has a solid plot.
映画の筋立てを簡単に説明してください。
Please briefly explain the movie's storyline.
Compound of 筋 (すじ, 'line, thread, logic') and 立て (たて, nominalized form of 立てる 'to set up, to construct'). Literally 'setting up the threads', referring to the construction of a narrative framework.