Lady of Darkness [Lady of Darkness Series, Book 1] - Melissa K. Roehrich

Owned by a ruthless Assassin Lord, Scarlett Monrhoe and her two sisters have been trained since they were children to torture and take life. They are the most feared trio on the continent, but they are also wild and unpredictable. A tragic night has Scarlett finding herself locked away in a noble’s household, trapped and forgotten, until she’s ready to fall into line.