In Milady's Chamber: A John Pickett Mystery (John Pickett Mysteries Book 1)

Low dealings in high society...
Estranged from her husband through her failure to produce an heir, Lady Fieldhurst resolves to repay his neglect by taking a lover. Fate takes a hand when she and her would-be lover enter her bedchamber to find Lord Fieldhurst lying on the floor--with her nail scissors protruding from his neck. Bow Street Runner John Pickett, twenty-four years old and new to the Bow Street force, has spent most of his brief career chasing petty thieves and pickpockets. Nothing in his experience has prepared him for low dealings in high society--or for the beautiful young widow who is the chief suspect.