Black-Haired Kerry and the Casebook of Romantic Troubles

In the nineteenth century, Kerry pretends to be a man and helps the powerless as a detective in London, though she's from an aristocratic family. She takes an assignment involving a stolen diamond for a couple who's facing their parents' objection. The man standing in front of her is Hohen, family lawyer with sharp stares. They're at odds against each other at first, but as they cooperate to solve the case, they become attracted to each other...?!