After a high-spirited but exhausting dinner party at the Mayfair home of American cinematographer Frederick Nolan, Rupert Mountjoy decides to accept an invitation from the gorgeous Amber Berlynne to catch a train up to Liverpool, and join a sporting party at Aintree racecourse for a spot of riding and the Grand National. However, before he leaves London, Rupert enjoys the ribald attentions of Becky and Dora, a pair of obliging working girls who both enjoy mounting a fresh young charger and getting the bit between their teeth.