One May Day a country boy escapes to London in the car of the amazing Mr Cat, stage musical star and champion fighter. Mr Cat sends the lad to his friend the Alderman FitzWarren who offers him lodgings and helps to find him a job as a city cook.
Dick befriends the Alderman's daughter Alice and seems to be on course for a happy life but alas, clouds soon beckon.
The head cook dislikes Dick. Even worse, a villain is in London's midst who can charm the birds off the trees and, it is rumoured, even the old moon down from the sky.
He is the master-rogue King Rat. He sneaks into houses of the rich at night, eats their food, dances till dawn with his rat kingdom and leaves a mess afterwards. He even persuades the poor to join him on his night jaunts.
King Rat's ultimate mission is revenge on Mr Cat for killing his father.
Yet his rat kingdom don't want to go out when Mr Cat is around. They fear him.
Luckily for them an Arab king invites Mr Cat and the Alderman to visit him. The king wants Mr Cat to kill the rats in his palace. He also wants to buy the Alderman's many antiques.
When they both sail away on the king's ship the rats begin their old antics. They start stealing food from the city hall where banquets and lunches are held.
Dick Whittington, the newcomer is blamed. He loses his job. Then the Alderman's return ship is lost at sea.
Although he loves Alice, Dick decides to leave London but the bells tell him to turn round. They say he will be Lord Mayor of London three times.
The Alderman's ship returns with riches. Mr Cat finds King Rat. They fight. Mr Cat defeats King Rat. Dick forgives him. King Rat charms all with his most powerful instrument. Suddenly people understand his success. They follow him.
A bereft Mr Cat goes to a park and sits alone. A cat fan appears who has gone to see him in his shows every night and wants to marry him.
She fetches the Classical Cat Quartet from a nearby hotel and makes him dance with her. They fall in love. They marry.
In a few years, Dick Whittington becomes Lord Mayor of London and marries Alice. Together they enjoy the wide variety of music offered by the city of London and mostly live happily ever after.