The whole story; all the particulars from beginning to end—the complete sequence of events or details.
彼は警察に事件の一部始終を話した。
He told the police the whole story of the incident.
録画に一部始終が残っていたため、すぐに真相がわかった。
Because the whole incident was recorded, the truth was discovered immediately.
彼女はその日の一部始終を詳しく説明した。
She explained in detail everything that happened that day.