The Voyage of the Jerle Shannara book 1 of 3,The Shannara series, overall ungoing

When the body of a half-drowned elf is found floating in the seas of the Blue Divide, an old mystery resurfaces. Thirty years ago, the elven prince Kael Elessedil led an expedition in search of a legendary magic said to be more ancient, more powerful, than any in the world. None of those who set out on that ill-starred voyage ever returned, until now. 

For the rescued elf carries a map covered with mysterious symbols only one man can decipher. That man is Walker Boh, the last of the Druids. But one other person understands the map's significance, the Ilse Witch, a beautiful but twisted young woman, who wields a magic as potent as Walker's own. She will stop at nothing to possess the map, and the magic it leads to. To stop her Walker must find the magic first.