Shadows of Camelot (Merlin's Legacy #4)

Truan Monroe, raised an orphan on an isle in the Irish sea, is a deadly warrior and sorcerer of awesome powers. Now, a startling vision of the past sends him through a doorway in time to a place where Merlin the magician has been banished for all eternity. Here, armed with the sword Excaliber, the Holy Grail, and the Prophecy of Cassandra, Truan wages war against Malagraine, Lord of Darkness, and struggles to save the life of the woman he loves.