The player characters are all Geatish heroes lately arrived at the kingdom of the Danes to help the beleaguered Hrothgar, whose mead hall has been overrun by...aliens from beyond the stars.
Of course, once Grendel--a xenomorph/human hybrid--has been slain and Heorot cleared of the alien menace, the heroes must venture beneath the lake to the crashed ship the xenomorphs arrived on and face Grendel's mother--the xenomorph Queen.
This statblock from Geek & Sundry may come in handy:
