One of Roald Dahl's. She tells him stories about witches, large nose holes, square feet, and disgustingly blue spit. The grandmother tells him that all the stories are true and he must always be on the lookout for them.
The boy’s grandmother gets sick and the two get forced to live in a hotel on the coast of England for her health to get better. While there, the boy finds himself locked alone in a room with two hundred witches. He hides behind a screen in the room and hopes the witches, who have an amazing sense of smell, will not find him. While there, he overhears the witch's amazingly evil wicked plan to turn children into mice by putting Delayed Action Mouse-Maker in chocolate bars in candy shops all around England. The witches demonstrate the Delayed Action Mouse-Maker on a boy named Bruno and he turns into a mouse. Bad news happens when one of the witches smells the boy behind the screen. The witches find him and he is unable to escape, he is turned into a mouse. After he becomes a mouse, he manages to escape their grip and runs away. He finds Bruno and they both go on an adventure to find the boy’s grandmother.
After a dangerous journey to his grandmother’s room, the boy tells her what happened. He still has his human voice. The boy and his grandma comes up with a plan to put the Mouse-Maker into the witches’ food while they are still at the hotel and turn them all into mice. He sneaks into the Grand High Witch’s room and steals some Delayed Action Mouse-Maker. Once completed, he goes into the kitchen and dumps it into the witches’ soup. The witches all turn into mice and are chased out of the hotel. The grandmother gives Bruno back to his parents. The boy has left a mouse for the rest of his life but decides that he is happy with life as a mouse. He does not need to do homework and can spend his life eating. He and his grandmother go back home and dedicate their lives to finding and destroying the witches.