Endless Knight by Annabel Chase

Return to the world of the Midnight Empire where darkness reigns and vampires rule.
New York is my prison.
Once a sought-after assassin, a single error in judgment landed me in servitude to House August, the most powerful vampire family in North America. Now I use my special brand of magic as a member of their security team, fighting monsters in the city and keeping the royal family’s many enemies at bay.
When the queen summons me for an assignment and offers my freedom in return, I want to jump at the chance—until she tells me what the assignment is.
Like a valiant knight, I am to escort her son from the family’s stronghold in Florida back to New York, which would be difficult enough without my messy romantic history with the rogue prince.
I accept the job because my freedom means more than my wounded pride.
Darkness and monsters stand between us and our destination. Thankfully I’ve never been afraid of either one.
I soon discover there’s more at stake than the return of the prodigal son. Even if we survive our enemies, I’m not sure I’ll survive the journey with the vampire who broke my heart.

Endless Knight, Midnight Empire: The Restoration, is the first book in a new urban fantasy trilogy set in the same world as Wild Knight, Midnight Empire: The Tower.