The Play
Luke, a British boy, goes to live with Helga, his Norwegian grandmother, after his parents are killed in a car crash. Helga tells Luke stories about real witches. As specified in the parents' will, Luke and Helga have to return to England.
They stay at a seaside resort, where Luke meets and befriends a gluttonous but friendly boy, Bruno Jenkins. Also staying at the hotel are a convention of witches, masquerading as the Royal Society for the Prevention of Cruelty to Children.
Luke inadvertently discovers the witches while playing with his pet mice inside the ballroom, where the witches hold their meeting. The Grand High Witch unveils her latest weapon: a formula to turn children into mice, which they will use on confectionery products in sweet shops and candy stores to be opened using money provided by the Grand High Witch. Bruno is lured into the room, having already been given chocolate laced with the formula a couple of hours earlier. He turns into a mouse. Luke attempts to escape but is also captured and turned into a mouse, though he avoids being squashed. He finds Bruno and reunites with Helga who recovered while Luke was adventuring.
Luke devises a plan and sneaks into the Grand High Witch's room to steal a bottle of formula. Luke manages to drop the bottle into a pot of cress soup destined for the witches' dinner tables. The formula turns all the witches into mice, just after Bruno speaks up to tell his father that he is really a mouse.