The poem is set in Denmark and Sweden, some time between 500 - 700 AD.
Grendel, a hideous monster, terrorises Heorot, the mead-hall (drinking hall) of Hrothgar, King of the Danes. Enraged by the noise of the partying and revelry, the monster Grendel launches regular raids, attacking at night and killing the King's greatest warriors.
This lasts for twelve years, until the hero Beowulf arrives. He is a Geat from southern Sweden, nephew of Hygelac, King of the Geats. Beowulf has heard of the troubles of Hrothgar, and arrives with fourteen warriors to help. Although he is at first challenged by guards who think he is a spy, they let him enter the country. He is welcomed warmly by Hrothgar, who knew his father, and by Queen Wealhtheow, and Beowulf tells tales of his brave exploits.
Unferth, a drunken warrior from Heorot, challenges Beowulf's bravery. Unferth claims that Beowulf lost a swimming race against Beowulf's childhood friend Breca; however Beowulf had been attacked by sea-monsters, and swam for seven days and nights fighting them. Beowulf in turn accuses Unferth of fighting and killing his own kin, and taunts him over his failure to kill the monster Grendel.
Beowulf decides to kill Grendel that night and boasts that he will do it bare-handed. He sits in the mead hall waiting for nightfall and the monster's arrival. Eventually, Grendel comes, breaking down the door and killing and eating one of Beowulf's men. Beowulf attacks the monster, wrestling him; his men attack Grendel with their swords but do no harm. With his mighty strength, the hero tears the arm off Grendel. The mortally-wounded Grendel escapes, running off to die, leaving a bloody trail that runs to its lair.
The following day, everyone celebrates, and Beowulf shows off the arm he tore from Grendel. There is a great feast, with singing, storytelling, and much praising of Beowulf. Only the scoffer Unferth is silent.
But it does not end there. Grendel's mother, a still greater monster, attacks the hall as her child had before. She grabs Hrothgar's counsellor Aeschere and vanishes back into the marshes. Beowulf and Hrothgar give chase, but the monster disappears under water. Beowulf follows alone, fighting off attacking sea creatures, until he comes to the monster's lair.
His sword will not harm her. She attacks him with a dagger, but his armour protects him. Luckily, in the underwater cave, Beowulf finds an enormous sword, forged by giants, and too heavy for any normal man to carry. Any man but Beowulf: he is able to pick up the sword, and swings it at Grendel's mother. He kills her, and, finding Grendel's corpse in the cave, cuts off its head as a trophy. Beowulf returns triumphantly to the Danish King. He is greatly rewarded, and goes back to his home in the land of the Geats, where he eventually becomes king himself after the death of King Heardred.
Fifty years later, the kingdom of the Geats is attacked by a fire-breathing dragon, angry that part of its treasure trove has been stolen by a Geatish slave, who was looking for money to buy his freedom.
Beowulf takes eleven warriors to fight it, but all except one, Wiglaf or Wicglaf, are scared and run away. Beowulf kills the dragon with Wiglaf's help, but Beowulf is bitten by the beast's poisoned fangs. He realizes he is about to die, and instructs Wiglaf to show him some of the dragon's treasure before he dies. He also tells Wiglaf to build a barrow (a memorial mound) to mark his remains, after his body is burnt on a pyre. Wiglaf returns alone to tell of Beowulf's great deeds. He banishes the cowards from the kingdom, and arranges for Beowulf's funeral, but new troubles are already brewing with neighbouring tribes.
This node is something of a mess already, so I will not try to contribute any description, commentary or prosodic analysis of the poem. However, one thing that is missing is a plot summary, which I hope I have provided.
[http://www.georgetown.edu/labyrinth/library/oe/texts/a4.1.html]. February 1, 2002. (Original Anglo-Saxon text.)
The British Library. "Beowulf" in Collections - Treasures. [http://www.bl.uk/]. February 1, 2002. (Cannot give URL of actual web page, the result of a search for "beowulf".)
Michael J. Cummings. "Beowulf: A Terrifying Tale of Good vs Evil: Background and Plot Summary". [http://zekscrab.users.50megs.com/beowulf/Plot.html]. February 1, 2002.
Grendel's Lair. "Grendel's Lair: Beowulf". [http://www.grendel.org/grendel/beowulf.html]. February 1, 2002.
Robin Katsuya-Corbet (ed.), "Beowulf".
[http://etext.lib.virginia.edu/cgibin/browse-mixed?id=AnoBeow&tag=public&images=images/modeng&data=/lv1/Archive/eng-parsed]. February 1, 2002. (Includes Gummere's translation.)
Kevin Kiernan (ed.). "Electronic Beowulf". [http://www.uky.edu/~kiernan/eBeowulf/guide.htm]. February 1, 2002.