The gentleman and his vowsmith
(Book)

"Lord Nicholas Monterris is trapped. The only heir to a declining dukedom, Nic is destined for a marriage of convenience. What he doesn’t expect is for his bride to be Lady Leaf Serral, daughter of his father’s hated rival. Tradition dictates the families are confined together while the marriage contract is crafted, which should be the worst part. Until Nic learns the Serrals’ head negotiator is master vowsmith Dashiell sa Vare—beautiful, perfect Dashiell sa Vare—an old flame he has neither forgiven nor forgotten. Nic’s only defense is false smiles and too much wine. When a dead body turns up, tension within the castle thickens. The first death is brushed off as an unfortunate accident, but a second reveals something sinister is unfolding at Monterris Court. As accusations fly and long-buried secrets surface, Nic must work with his former lover and his future bride to uncover a devious mastermind before they claim another victim." --publisher's website.