The Viscount’s Dangerous Liaison by Louise Allen

Theo’s an Earl with a problem. Laura’s a lady in hiding. Life’s complicated enough without a traitor, smugglers and murderous mayhem getting in the way of their fragile romance.
Laura Darke wants to keep out of the hands of her scheming trustee. Theo Quenten needs to come to terms with proposing to a lady he doesn’t love. When they both find themselves in a country house on the Norfolk coast things are complicated enough without mysterious tombs, a murderous attack on the curate, French gold and smuggling parsons. Somehow Theo has to free himself honourably, Laura has to thwart her relatives and together with their friends and some highly suspicious allies, bring a traitor to justice. Includes a valet in drag, a long-dead Rector, a gang of smugglers and familiar faces from the first two books in the Dangerous Deceptions series: Loving the Lost Duke and The Swordmaster’s Mistress.