A brief outline or summary of a story, argument, or text — the main points arranged concisely.
本のあらすじを読んでから買うかどうか決める。
I'll read the book's summary before deciding whether to buy it.
映画の粗筋を友達に説明したら、興味を持ってくれた。
After I explained the movie's outline to my friend, they became interested.
レポートの最初にあらすじを一段落でまとめよう。
Let's summarize the report in one paragraph as an abstract at the beginning.