Crown of Smoke (Kingdom of Sinners) by Ajme Williams

What’s worse than sleeping with a stranger?
Finding out he’s a ghost.
Then learning you’re pregnant with his baby. I was just chasing a mafia story.
One reckless lead, one dark alley, one heartbeat from death...
Until his fists saved me. Blood-spattered knuckles. Steel in his eyes.
"Ask about the Keans again," he growled, "and I won't be there next time." Flynn Tine was supposed to be one dangerous night.
A forbidden rush wrapped in muscle, shadows, and secrets.
 Except Flynn doesn't exist. His real name? Flint Ifrinn.
The rightful heir to a criminal empire the Keans burned to ashes.
The vengeful phantom I should have fled from...
Not let claim my body and mark my soul. Now I'm pregnant with the heir to a dead dynasty.
Ronan Kean has me captive.
And Flint is ready to paint Boston red to reclaim what's his. My story. His revenge. Our child. 
Let the bloodbath begin.