The Heart of Shadows — Robert E. Keller

An ancient evil haunts the land, and old enemies have returned to kill Lannon Sunshield and destroy Dremlock Kingdom. The long winter is coming to an end, but the icy, bitter touch of the Deep Shadow has grown even colder. With a prolific assassin on the loose, no one can be trusted. Meanwhile, the shadow of an expanding kingdom at last reaches Silverland, promising war.