Assassin's Heart, book 1Sarah Ahiers2016

Seventeen-year-old Lea Saldana is a trained assassin. She was born into one of the nine clipper Families in the kingdom of Lovero who lawfully take lives for a price. As a member of the highest-ranking clan, loyalty to Family is valued above all, but that doesn't stop Lea from getting into a secret relationship with Val Da Via, a boy from a rival clan. Despite her better judgment, Lea has fallen in love with him; but she's confident she can anticipate any threat a mile away.Then she awakens one night to a house full of smoke. Although she narrowly escapes, she isn't able to save her Family as their home is consumed by flames. With horror, she realizes that Val and his Family are the only ones who could be responsible. Devastated over his betrayal and the loss of her clan, there's just one thing on her mind: making the Da Vias pay. The heart of this assassin craves revenge.