The Ghosts of Ardenthwaite — Harriet Smart

Something is amiss at Ardenthwaite. Ghostly apparitions have been seen, so terrifying that the mistress of the house and the servants have deserted the place. Colonel Parham, the tenant, asks his landlord Felix Carswell and Major Giles Vernon to determine what is going on. But their investigations soon takes an unexpected turn, leaving them in confusion and doubting their own sanity.
Shortly afterwards, a man dies in Northminster Infirmary, the victim of a brutal and systematic attack which seems to point to dangerous criminal forces hitherto unknown in the city. Vernon has his suspicions as to who is behind it, and with Carswell's assistance he begins to unpick a complex network of alliances and enemies. Yet, as their best witnesses meet brutal fates, they are forced to face the grim possibility of failure.
Having been forced into unpleasant compromises to gain access to the truth, Giles is further unsettled by the return of Emma Maitland to Northminster, now engaged to another man. As she assists him with the case, he begins to realise all that he has lost. For Felix Carswell, a bizarre and other-worldly encounter with a beautiful, spirited young woman throws up the possibility of an extremely advantageous marriage. Eleanor Blanchfort is an heiress and Lord Rothborough's ward. Has destiny brought them together as she suggests, and can Felix find the will to resist such a dazzling temptation?

The Ghosts of Ardenthwaite is the fifth novel in Harriet Smart's Northminster Mysteries, featuring intrepid early Victorian detectives, Major Giles Vernon and Felix Carswell.