Beowulf slays grendel to

Grendel has been aimlessly and joyfully murdering the people of Heorot. Thus, Beowulf, goes to offer his services to Hrothgar. Upon his arrival, Beowulf introduces himself as a hero who can crush water sprites, among other things. Therefore he is equipped to defeat Grendel, if Wyrd (or Fate) will have it so.