A Spinster for the Rakish Duke by Ava MacAdams

There is no telling where a scandal might lead…

A spinster and a bluestocking, Miss Emma Bradford does not regret sacrificing her happiness to raise her siblings. She does regret sending a very scandalous letter to her pen pal though.
Sick and tired of being chased for his title and wealth, Donovan Connor, the Duke of Lowe, deems it best to hide his true identity from the only woman who dares address him as an equal.
With Emma being forced to marry against her will and her brother Benjamin disappearing, the only way for Donovan to stay close to her is by pretending to be an investigator. What he never expected though was that he would end up being the main suspect of the crime.

*If you like a realistic yet steamy depiction of the Regency and Victorian era, then A Spinster for the Rakish Duke is the novel for you.