High King by Kathryn Le Veque

Love is immortal and time, as we know it, is circular. Souls never truly die, but connect with each other in different times, different worlds.

A modern American girl is about to discover just how mystical the world can be.
And just how much she loved an ancient king… and was loved in return.
Destry Caldbeck, smarting from being jilted at the altar, travels to Ireland on what was supposed to be her honeymoon. While visiting Dowth, an ancient Neolithic site outside of Dublin, she encounters a group of students and their instructor. Dr. Conor Da Derga is everything an Irishman should be – enormous, muscular, red-headed, and drop-dead sexy. He’s also loud, booming, animated, and brilliant.
Conor, having seen the gorgeous American with the bright eyes when she first arrived at the mound, is thrilled to have a chance encounter with her. Destry and Conor share a moment of undeniable attraction before ancient incantations and ghostly visitations begin to lend clues to their past lives as an ancient king and queen. Soon, they find themselves caught up in a maelstrom of time shifts, landing them back in the Middle Ages of Ireland’s history where they discover a high king’s destiny.