What is the main conflict in Beowulf the Warrior by Ian Serraillier?

Beowulf the Warrior tells the story of a great Geatish warrior who travels from modern day Sweden to Denmark to rid the Danes of a vicious monster called Grendel who has long been slaughtering the finest of the Danish warriors. With his great bravery and cunning Beowulf will forge a bond between the Danes and Hrothgar, King of the Danes, who, till then, had been enemies. After killing Grendel, Beowulf must also kill the monster's mother before he can return to Geatland.