Anne Cartier and her husband Paul, Provost of the Paris Highway Patrol, are spending the winter in Nice. Anne hopes that the milder climate and enforced break from work will cure her husband's chronic cough. But when news reaches them of the escape from Toulon naval prison of convict Jean Lebrun, Paul cannot resist the temptation to investigate.

January 1788. Anne Cartier and her husband Paul, Provost of the Paris Highway Patrol, are spending the winter in Nice, at the home of a wealthy English couple, Thomas and Beverly Parker. Anne hopes that the milder climate and enforced break from work will cure her husband's chronic cough. But when news reaches them of the escape from Toulon naval prison of convict Jean Lebrun, imprisoned 20 years earlier for the apparent murder of his master, Paul cannot resist the temptation to investigate. Together with his adjutant Georges, still based in Paris, he makes enquiries that lead the team to believe that Lebrun was innocent, and unjustly condemned. Anne, meanwhile, has been drawn against her will into the unsavoury affairs of the expatriate community of Nice - a motley collection of characters all with their own reasons for being there...