In Milady's Chamber (John Pickett Mysteries, #1)

Low Dealings in High Society...
Estranged from her aristocratic 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 paramour enter her bedroom and find Lord Fieldhurst lying on the floor-with her nail scissors protruding through his neck.
Idealistic young Bow Street Runner John Pickett has spent most of his brief career chasing petty pickpockets. Nothing in his experience has prepared him for low dealings in high society-or for the beautiful widow who is the chief suspect.
The popular press sees the case as a classic lovers' triangle and expects a quick arrest, while back in Bow Street, the magistrate questions Pickett's handling of the case in the light of his unprofessional interest in Lady Fieldhurst. Under increasing pressure from without and within, Pickett must uncover the true murderer if he is to save an innocent woman from the gallows.