Houston Attack (Hawker Book 5)

Hawker infiltrates a human trafficking operation at the Mexican border
 
In a forgotten town on the wrong side of Texas, James Hawker stumbles into a fetid dive bar. The most dangerous vigilante in America is blind drunk, and stinks of mescal. He begs the bartender for help getting back across the border, and the man obliges—for a fee. He introduces Hawker to a pair of toughs, who chain him up in the back of a truck and begin the long trip north. Hawker has been captured by a modern-day slaving outfit—and it’s exactly what he had in mind.
 
Hawker’s nationwide war against organized crime has led him to Houston, where the land barons of Texas have found a way to save money on labor: Capture vagrants in Mexico and put them to work as field hands—and worse. To break the slave ring, Hawker has placed himself right in the line of fire.
 
Houston Attack is the 5th book in the Hawker series, but you may enjoy reading the series in any order.