Dangerous Vows by M. James

My marriage will stop a war between our families. But it’s a marriage begun on a lie…

There’s only one man in Chicago more powerful than my brother, the newly minted pakhan of the Vasilev Bratva–and that’s Theo McNeil, the leader of the Irish Kings in this city. A man I don’t know and have rarely seen, Theo is whispered to be a brutal man, even more violent and steeped in blood than my brother.
And he’s going to be my husband.
When Theo turns his eyes on the still-fragile territory that belongs to my brother, the only way to stop him from destroying what’s left of our family is by agreeing to marry him. I have no choice–I’ve known all my life that this is what I’m meant for. That my duty is in offering up my hand in marriage–and my innocence–to bridge an alliance and stop a bloodbath.
Except I have no innocence left to give. And the man who claimed it wants me for himself.
With my loyalties split and these dangerous vows made, who will I choose to love in the end?