It is the third book of the series The cold-hearted Vampire and the slave.
Alisha, Sofia, Josh, and all his friends and cousins have found their mate or beloved. And they all are happy with their mates. But Jared wasn't able to find his mate after so many centuries and almost start to lose hope of finding her. So one day on his mother's advice he decided to go and visit a witch.
From here, he found out that his mate hasn't born yet. She will take birth after some centuries as a human princess as a daughter of Queen Elena and the king Martin of New York.
So he leaves for New York City to their palace. What happens after then for that you have to read the book.