In the broom cupboard of a small dwelling called Rose Cottage, stands a house fit for a mouse - well, two mice actually. A house made of pebblestone, with gables on the windows and turrets peeking out of the roof. A house with a ballroom, a billiard room, a banqueting room, a butler’s room and a drawing room. The house belongs to Mr and Mrs Nutmouse, or Tumtum and Nutmeg as they affectionately call each other.

Tumtum and Nutmeg have a wonderful life but the children who live in Rose Cottage, Arthur and Lucy, are miserable. So, one day Tumtum and Nutmeg decide to cheer them up … Tumtum repairs the electric heater in the attic where the children sleep and Nutmeg darns the children’s clothes. Arthur and Lucy are delighted and think a Fairy of Sorts is looking after them. But then Aunt Ivy with her green eyelids and long arms arrives. She hates mice and hatches a plan to get rid of them. Soon Tumtum and Nutmeg are no longer safe to venture out …