A Little Boy is just trying to go to sleep when a Little Monster creeps up to his window and . . . says goop-zee-googy! Or, peek-a-boo!, in case you don't speak Monster. Hilarity ensues as the Little Monster tries to play with the Little Boy despite the language barrier. While at first scared, the Little Boy comes to Little Monster's rescue when he gets hurt and the two new friends are able to play together all night long.

Complete with a glossary translating the monster language used throughout, this classic nighttime adventure story will have little readers wishing for a Little Monster to knock on their window at night.