Timothy is a proud city mouse. One day he looks in the mirror and sees he has changed. In fact he frightens himself so much that he runs out of the house, out of the city and makes his way to the quiet of the country. There he meets Spinny, a young mouse, who invites him to live in the 'Castle' with the other mice. But to join them, Timothy, now known as Mr. McMouse must get a license. Will he be able to earn a license?