Fallowblade: The Crowthistle Chronicles Book #4

The fourth book in the Crowthistle Chronicles. War engulfs the kingdoms of Tir. Invading armies are marching north and it seems that all is lost . . . Until a new peril looms; a far more deadly menace that threatens the entire human race. Out of this chaos emerges a stranger, a supernatural knight whose shadow-torn hair falls like the evening wind. When Asrāthiel saw him she gasped, for he was so beautiful it was like pain to look at him...

'Dart-Thornton conjures up her world of Tir in the luminous yet hard-edged manner of Jack Vance and Mary Gentle' - The Washington Post -