What is the initiating event?

Much of the beginning is concerned with genealogy. The initiating event is probably after Horthgar builds the great Heorot Hall. Once the hall is finished, Hrothgar holds a large feast. The revelry attracts the attentions of the monster Grendel, who decides to attack during the night.This attack initiates the rest of the story. You will have to scan your copy of the play. Different publications have different page numbers.