When his nagging mother discovers a rat infestation, the anonymous writer of these notebooks sets out to drown the pests, but finds himself unable to go through with it. Instead, he befriends the rats, learning to train and communicate with them.

Before long he has the idea of using the rats for revenge against a world in which he has been a failure. His target is his hateful boss, Mr. Jones, who treats him with supreme disrespect and plans to fire him and replace him with someone less expensive. The narrator records his plans in chilling detail as his campaign for vengeance progresses from vandalism to robbery to the most horrific of murders...