I have been a huge fan of both mythology and D&D for the better part of 30 years now and I had to point out what a wonderful job issue #329 did on the Celtic version of Beowulf. However, at the same time I would like to point out the the Norse version of the Myth is about 200 years older than the one represented in the article.
I am not bringing this up in order to downplay the content of the article in any way, but to bring other possile plot hooks into play.
Even in the Norse version of the story Beowulf is a Geat warrior of great renown who sailed to Denmark to help King Hrothgar face the monster Grendel. The main differences are the facts that the Norse refer to Grendel as a swamp troll and that during their battle Beowulf cut off Grendel's arm with a sword, causing him to run away.
The rest of the story plays out the same way as it did in the article. Grendels mother comes back to avenge her son and Beowulf pursues he into her underwater cave where he cuts oof her head. The Norse version never actually mentions the death of Grendel.
It also never mentions Beowulf putting fire to the troll. In Norsed mythology this fact doesn't matter, but it makes a huge difference in D&D. From the game perspective, two very angry and vengeful trolls could really reek a lot of havac!