The Assassin's Mark - Edge of Oblivion, #1

An assassin becomes a protector as he enters a magical world.all for the woman of his dreams. Brigit Ó Ruaidh is the sole heir to the Kingdom of Freehaven. While journeying to visit a lord, she learns her royal parents have been murdered...and she's next. With assassins after her, she tries to prevent her kingdom from falling into anarchy. As she sets her eyes on the throne, her world gets turned upside down when she's rescued by a dangerous man.
Edward Emerson is an assassin. His job is to kill those who bring death and suffering to his world. When he finds himself in another world protecting a princess he's seen in his dreams, he vows to move heaven and earth to keep her safe. In return, he hopes to find his way back home. Another claimant to the throne blocks their way, and he will risk everything to make his mark on Freehaven and carve out power of his own.
If Brigit and Edward don't work together, they won't live long enough to see her reclaim her destiny...or for their love to blossom.