''Beowulf'', set in Scandinavia, is one of the most important Old Anglo-Saxon heroic epics, and tells us about the adventures and deeds of Beowulf, the hero.
Beowulf is a Geat (a tribe or people) and is requested by the Danes to help them, as they are under attack by a terrible monster/creature called Grendel. Beowulf goes willingly in response to the Danes's king, Hroogar, and waits at night in the 'mead hall' (a place where the Danish warriors dwell and have their feasts etc) for grendel to make it's nightly attack. When Grendel finally arrives, Beowulf attacks it in return and chases it and slays/kills it.
This is the end of the first fight, that of Beowulf against the Grendel-- but he and the Danes have reckoned without Grendel's mother, an even more terrible monster, who now comes to exact revenge for the slaying of its child or offspring. When Grendel's mother also attacks the Danish mead hall, she is slain by Beowulf too, after a big fight. He is thus now the celebrated hero, the slayer of two evil monsters, famous and held in great reverence. After receiving popular acclaim and gifts from the Danes, Beowulf then returns to Geatland, in due course becoming the King of the Geats.