When Tom's brother Peter will get measles, he's despatched to stick with his Uncle Alan and Aunt Gwen in a flat with no backyard and an aged landlady, Mrs Bartholomew, residing upstairs. As a result of he could also be infectious, he's not allowed to play exterior and feels lonely. With out train he's much less sleepy at evening and when he hears the communal grandfather clock surprisingly strike 13, he investigates and finds the small again yard is now a big sunlit backyard.
