The narrative opens on Derby Day in London, where Viscount Medenham, a restless wanderer recently returned from Africa, encounters his former artillery driver, Simmonds, whose car has been disabled in a collision. Eager for an adventure and sympathetic to Simmonds's plight, Medenham seizes the chance to step into the driver's seat and take charge of Simmonds's wealthy American clients for a ten-day tour to Brighton. Posing as a professional driver named George Augustus Fitzroy, Medenham finds himself responsible for Cynthia Vanrenen and her sophisticated, snobbish chaperon, Mrs. Devar.
Throughout the journey, Medenham balances his true identity with his duties, deftly navigating chance encounters with old acquaintances and outwitting the persistent, fortune-hunting French Count Marigny, who has laid his own elaborate plans to win the heiress. As the tour winds through the leafy lanes of Surrey, Hampshire, and the picturesque Wye Valley, Cynthia and her incognito chauffeur grow increasingly close, sharing quiet moments that transcend their artificial social divide. Complications multiply when Medenham's father, the Earl of Fairholme, arrives in pursuit, spurred by gossipy letters from society friends convinced that his son has fallen into a trap. Amidst mistaken identities, clandestine telephone calls, and unexpected detours, Medenham must find a way to reconcile his aristocratic duties with the genuine affection he has developed for Cynthia, all before the tour reaches its inevitable conclusion in London.
