In the broom cupboard of a 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.When General Marchmouse unexpectedly joins the Nutmouses on a camping trip things soon begin to go horribly wrong. Before they know it, the mice are whisked downstream on Arthur´s toy boat Bluebottle. The General soon spies an island in the distance that he is determined to explore - and fiddlesticks to anyone who disagrees! But once ashore the mice soon find that they are not the only ones to have discovered the island...