Bushwack bullets

"Hap and Everett, adopted children of the Yaqui County sheriff and his wife, were known as the Kingman twins. Actually Hap was the son of the upright rancher Warren Allen, who had been killed by bushwack bullets, while Everett's father was the ruffianly cattle thief, Dev Hewett. The boys were ignorant of their own identity until they came of age. And then, for reasons of his own, the crooked lawyer entrusted with telling them the truth pretended...