The Outlaws — Jane Toombs

After Billy the Kid and Mark Halloran rescue what's left of the Nesbitt family from an Apache attack in the New Mexico Territory, the fate of the young daughter and the teen-age boy are sealed. Tessa's attracted to Mark and Ezra suffers a severe cause of hero-worship over Billy, wanting to be just like him. Soon all of them are involved in the cruelest range war in the history of the West--the bloody Lincoln County war. How can Tessa protect her brother from trailing after Billy? And how can she be drawn to a man who is on the opposite side of this range war?