The Lunatic, The Doctors, and The Daemonologist.

The 4th mystery, set in the early 1800s in which there is much madness. Considered a prequel to The Maiden and the Shadow.

Cast
 Gabriel Carter. An extremely rich and universally hated miser

 Benjamin Davies. His browbeaten chief clerk

 Patience Martins. His tyrannized maid, who harbours an increasing desire to murder him

Peter Carter. His estranged nephew, a gentleman scientist

 Annie A bright street urchin whom the scientist occasionally scrubs up and uses as a messenger and lab assistant

 Joshua Shaw. The much-maligned chief doctor of the York Lunatic Asylum

 James Griffin. A promising junior doctor of the Asylum

 Sarah Carter [Elizabeth Haines]. An escapee from the Asylum

 Catherine (Kate) Allesbury. An aristocratic ex-lunatic, who was let out of the asylum upon the king's remission, perhaps prematurely

 Matthew Murrey. A notoriously corrupt magistrate with a thing for deportation

 Emeline St. Oswald. A wealthy philanthropist dedicated to improving the lives of the poor and dispossessed

 William Allesbury. A dashing gentleman explorer, back from his recent trip out to the East Indies

 James Edwards A solicitor

Before the action
It hit the headlines recently that a dishevelled lunatic escaped recently from York asylum. Know to only few, this was in fact the niece and ward of the rich miser Gabriel Carter, who had conspired to have her confined there. Having been told that she is visiting her aunt in Scarborough, her brother Peter tried to visit her, and on the day of the mystery is returning to York to have the truth from Gabriel.

The previous day, Benjamin Davies had bought an interesting trinket to woo his love, which had caught the eye of the opportunist orphan Annie, who is seeking to be named heir to Emeline St. Oswald and knows a certain necklace will support her claim.

Benjamin Davies, clerk, and William Allesbury, gentleman explorer, are competing for the heart of Emeline St. Oswald, and Dr. Joshua Shaw is attempting to pull York asylum through it's upcoming inspection.

During the day
Sarah Carter fell gradually in love with her rescuer James Griffin, and they became betrothed.

Annie became heir to Emeline St. Oswald.

Gabriel Carter was shot in York minster by Catherine Allesbury, who was driven by the voices in her head.