- Movietrailer -
In 2007 the movie "Beowulf" was shown. But the story is not exactly the same as the book.
Here is a short summary:
Grendel kills a lot of Hrothgar's people, so Beowulf calls his stringest warriors and sails to the Danes. In a pretty short fight he kills Grendel, just like in the movie. His mother gets angry and gives ad nightmares to Beowulf and kills all his men. So he goes to the Demon's cave with his best and only warrior left. But when he sees Grendels mother, he falls in love with her and gives her a baby to put the spell off the people and become a king of a great empire. He also had to promise that the golden horn he got from Hrothgar may not find its way back to the castle.
When Hrothgar hears of the news, he says that he "is free now" (because he did the same mistake with Grendels mother before) and kills himself. So you can think that Grenel is Hrothgar's son.
Then, many years later, Beowulf is the new king, the humans find the golden horn. Beowulf wants to bring it back to the demons, but his son, who has become a huge dragon, attacks the castle and tries to kill Beowulf's wife and girlfriend. Beowulf tries to stop him, but he has to cut his arm to reach the dragon's heart. This way he killes the dragon but also himself.
The dragon becomes a human figure but before they can talk he disappears in the sea. Beowulf's warrior becomes the new king but it is not said what would happen next, or what happened with Grendels mother. (open end)