Mistress of Sin by Jade Fierro

When a marriage between the powerful Moretti and Vitale families is meant to end generations of bloodshed, an unexpected attraction develops between their newly connected daughters. Elena Vitale is fearless, cunning and impossible to ignore, challenging every boundary her new stepsister tries to maintain.

As their forbidden feelings intensify, the fragile peace between their families is threatened, forcing them to choose between loyalty, survival and a dangerous love that could reignite an all-out war.