A Murdered Earl - Romantic Suspense, #1

Comte Luc de St Pierre du Vivier lost his father to the guillotine, his mother to grief, and his inheritance to the revolutionaries. He becomes Luke Peters when forced to earn his living in England. All he saves is his sister Sylvie, now living with their English grandparents in an Oxfordshire vicarage, and a rumour of jewels secreted by his father, and connected in some way to the Earl of Redditch.
When the Frenchman Bossard is seen in Oxford, intent both on revenge for his fellow revolutionary's death at Luke's hands, and on forcing Sylvie to reveal the secret of the hidden jewels, Luke finds employment at the Earl's London house. He hopes to conceal where Sylvie lives. Promoted to valet, he is suspected of murder when the Earl dies. Cyanide has been added to his morning chocolate. To clear his name Luke must discover which of the Earl's unpleasant family or disaffected servants is responsible. Is it the extravagant Countess or the feebly lecherous Viscount? Might the whining nephew Frederick and his plebeian wife Amelia, who seem to care only for their brattish son Willie, have somehow arranged it? Could it be the butler, summarily dismissed, the cook who flounced out in a fury, or any of the other servants? The Earl was a difficult master.