Companion to the Count by Melissa Kendall

The only thing more dangerous than a secret is the man who holds it.

Saffron Summersby lost everything after her brother’s suspicious death: her dresses, her dowry, her place in society as a baronet’s sister. So when she sees her brother’s face in the latest painting from famous anonymous artist Ravenmore and realizes he might still be alive, she comes up with a plan: learn the identity of the painter, find her brother, and save her sister from marrying a brute in order to avoid financial ruin. She doesn’t expect her investigation to lead her into the den of a notorious rake.
After the death of his sister, Leopold “Leo” Mayweather, Viscount Briarwood, gave up his wild ways and devoted his life to art, particularly the distribution of paintings by the reclusive Ravenmore. So when he discovers someone is stealing the paintings and replacing them with forgeries, he decides to host an art auction to draw out the thief. He doesn’t expect a beautiful woman to storm into his life, determined to unmask Ravenmore.