Eddie meets Grendel the junk monster, who conspires with him to leave his room in a mess. Through a series of adventures, Eddie discovers that being neat has definite rewards.
Eddie never throws anything away. He never puts anything away, either. When his mother goes on strike and refuses to clean his room anymore, Eddie shoves everything into a hug pile in the corner. One night the pile comes to life. Eddie has unwittingly created a monster. It calls itself Grendel, and it begins to dominate Eddie's life, growing in size with each possession Eddie fails to put away. Eventually Eddie realizes that unless he does something about it, Grendel, actually a professional and experience monster, will leave him with nothing.