A Hanging at Lotus Hall - The Steampunk Detectives, #2

Family secrets are the most dangerous.. All is not well at Lotus Hall, the home of the Dukes of Bennington, powerful mages who sit at the highest levels of power in the British Empire. Consulting detective Gregor Sherringford, youngest brother of the current duke, is summoned home by his mother, the Dowager Duchess, after the mysterious arrival of a family member long presumed dead. Joan Krieger, Gregor's investigative partner and lover, accompanies him, though the summons is badly timed.
Gregor has been pushing her to get married while Joan, who saw the ruins of a marriage destroy her parents, balks. In her experience, families bring nothing but grief. Besides, she's no proper match for Gregor, with her reputation as a "fallen" woman, and being from a Jewish merchant family. Her fears are realized after their arrival at Lotus Hall. The duke is distant, Gregor's mother is concealing a secret about the long-lost family member,  Gregor's other brother is hiding an affair that could bring scandal down on the family, and the other guests, important members of the Metaphysical Society, warn Joan of dire consequences if she continues to use forbidden magic in her investigations.
When one of the signature Sherringford inventions is used to kill, uncovering the truth behind all the facades becomes imperative. For someone is hunting Sherringfords and unless they can all learn to trust each other, their family will be utterly destroyed.