The plague of swords Traitor son cycle, book 4.

With more at stake than ever before, The Red Knight faces an uncertain future and is forced to team up with old enemies to defeat a greater evil in the fourth book in the Traitor Son Cycle. One enemy has fallen. But a greater one still remains. Now, it's war. With one army defeated in a victory which will be remembered through the ages, now the Red Knight must fight again. For every one of his allies, there is a corresponding enemy. Spre...