In the original tale of Beowulf, Grendel was purely a monster. Gardner's novel focuses on the part of the original Anglo-Saxon epic that points out Grendel came of "the race of Cain"--in other words, he was a human being, but cursed. Gardner's Grendel imagines what it must have been like to be Grendel, capable of human thought and speech and feeling, but treated as vermin, the ultimate vengeful outcast. It uses Grendel's point of view to ask the question, "What does it mean to be human?"