In the summer of 1947, Britain prepares to commemorate the wedding of Princess Elizabeth and Prince Phillip. To get around food-rationing laws, Dr. Charles Swaby, accountant Henry Allardyce and solicitor Frank Lockwood are fattening a black-market pig for the big day. Egged on by his wife, meek Gilbert Chilvers steals the swine, but the couple must conceal it from inspector Morris Wormold.