Two veteran cars and their crews participating in the annual London to Brighton Veteran Car Run. Alan McKim (John Gregson), a young barrister, and his wife, Wendy (Dinah Sheridan), drive ''Genevieve'', a 1904 Darracq and Company London. Their friend Ambrose Claverhouse (Kenneth More), a brash advertising salesman, his latest girlfriend, model (person) Rosalind Peters (Kay Kendall), and her pet St. Bernard (dog) ride in a 1905 Spyker.