In this book, Grover is horrified to learn that there is a monster at the end of the book, and begs the reader not to finish the book, so as to avoid the monster.
Fearful of reaching the end of the book, Grover constructs a series of obstacles, such as attempting to tie pages together and laying brick walls, to prevent the reader from advancing.
Increasingly frightened (and also in awe of the reader's strength at overcoming the obstacles), Grover pleads with the reader to stop reading as the book nears its conclusion.
However, the monster turns out to be Grover himself, making the story self-referential. Grover jokes that he tried to convince the reader that the monster would not be scary - but we see at the end that he is embarrassed.
A sequel, Another Monster at the End of This Book: Starring Lovable, Furry Old Grover, and Equally Lovable, Furry Little Elmo (ISBN 0-375-80562-1), was published in 2000. It was also written by Stone and illustrated by Smollin, and features Grover and the ubiquitous Elmo.