The book features two characters, a mouse and a boy. Only the mouse speaks; his words are reported indirectly by a narrator.
The boy gives a cookie to the mouse. To eat the cookie, the mouse asks for milk. The mouse then requests a straw (to drink the milk), a mirror (to avoid a milk mustache), nail scissors (to trim his hair), and a broom (to sweep up). He then wants to take a nap, to have a story read to him, to draw a picture, and to hang the drawing on the refrigerator. Since looking at the refrigerator makes him thirsty, the mouse asks for a glass of milk, and "he's going to want a cookie to go with it."