Manners and Monsters by Tilly Wallace
A lady never reveals the true extent of her decay...
Hannah Miles lives a quiet existence, helping her parents conduct research into a most terrible affliction - until a gruesome murder during her best friend's engagement party pulls her from the shadows. With her specialist's knowledge and demure disposition, Hannah is requested to aid the investigation.
Except Hannah discovers her role is to apologise in the wake of the rude and disgraced man tasked with finding the murderer. The obnoxious Viscount Wycliff thinks to employ Hannah purely as a front to satisfy Whitehall, but she'll have none of that.
The two must work together to find the murderer before the season is ruined. But the viscount is about to meet his greatest challenge, and it's not a member of the ton with a hankering for brains.