The Hermit by Michelle Heard

I entered an arranged marriage so my sister, Ciara, could marry for love. Three years later, I’m a widow, and my father arranges for Ciara to marry Dominik Varga. The assassin slash arms dealer is as dangerous as he’s quiet, which is very unnerving.
Needless to say, I’m not happy at all. A deal was a deal, and I kept my end of it, so there’s no way on God’s green earth I’ll just sit back and smile like a good little girl. I’ll fight for Ciara’s freedom so she won’t have to face the hell I was forced to endure.
But Dominik doesn’t make things easy for me. He’s determined to get his hands on half of Dad’s empire.
When he moves into my family home, my entire routine unravels. I have to fight for more than just my sister’s freedom because I’m in danger of losing my heart.

I refuse to admit I’m drawn to his darkness. If I do, God only knows whether we’ll survive the fire raging between us.