Showing Face Down in the Marrow-Bone Pie by Kathy Lynn Emerson

When the steward at her husband’s Lancashire estate dies under mysterious circumstances, Susanna, Lady Appleton suspects he was murdered. As an expert on poisonous herbs, she sets out to discover the truth but ends up unearthing more secrets than she bargained for. First book in the FACE DOWN mystery series by Kathy Lynn Emerson; originally published by St. Martin's Minotaur and Kensington Books