Vengeance Is Mine — William W. Johnstone

They've already started coming across. The drug dealers and the petty criminals. The terrorists and the parasites. For one man on the West Texas border, the time to stand against them is now. John Howard Stark, a Vietnam vet whose family has worked their ranch for generations, has set off a trip wire--and an ambush has exploded all around him. A Columbian drug cartel commander, with the help of an ex-special forces hit man and his own deadly army, has killed three Americans--including Stark's uncle and his neighbor--and will slaughter anyone else who stands in his way. The local law is in his pocket and the Border Patrol is powerless to help.

Now John Howard Stark is about to wage a one-man war. And he's got the best kind of reason to fight to the death. But for this American, there's one thing more dangerous than the enemies slithering across the border--and that's the second enemy standing behind his back: His own government...