In grendel, john gardner uses

In Grendel, John Gardner uses a dark pessimistic tone and menacing diction to examine the world of the monster, Grendel.

As you may recall from Beowulf (if you haven't read this one), Grendel is the monster who terrorizes and murders people until Beowulf comes to stop him. Well, this book looks at the whole story from Grendel's perspective and sheds a different light on him.