The most basic genre of Walter Dean Myers's Monster is fiction. Within this, the book could be called a young adult novel, a crime novel, or a courtroom drama. Much of the book is also written as a screenplay.

There are several different ways of describing a work of fiction. One is to summarize the plot. Another is to talk about the themes and the way the author explores them.

A brief description of the plot of Monster might be as follows. Steve Harmon is a teenager from Harlem who is accused of playing a part in a robbery which turned into a murder. Although Steve is not even accused of having played any part in the violence, the prosecutor describes him as a "monster." The book follows Steve through the trial day by day and, since he is obsessed with film, much of it takes the form of a screenplay. Although Steve is eventually acquitted, he still feels that those around him, including his family, see him as a monster.

One of the central themes of the book is the difficulty of escaping from an environment marked by violence and poverty. Steve is a harmless and well-meaning person who wants to be left in peace to make documentary films. He is pressured into peripheral involvement in crime and condemned as a monster because of the neighborhood in which he has to live. Monster explores this unjust situation from the viewpoint of a victim who only barely survives.