Florida Firefight (Hawker, #1)

A disgraced Chicago cop launches a one-man war against organized crime
 
A man holds twelve children hostage at gunpoint. Across the street, James Hawker dangles from a skyscraper, watching the terrorist through a sniper’s scope. Hawker has a shot, and he wants to take it, but the police brass say no. By the time he gets permission, it will be far too late. The terrorist opens fire, killing two of the children before Hawker can take him out. When the smoke clears, the madman is dead, and Hawker’s career is toast. No longer a cop, he’s about to become America’s deadliest defender.
 
The father of one of the murdered children hires Hawker as a private vigilante, and gives him an unlimited bankroll to wage a nationwide fight against organized crime. The first battle will be fought in Florida, where drug smugglers have taken root like a cancer—and Hawker will have to cut them out.
 
Florida Firefight is the 1st book in the Hawker series, but you may enjoy reading the series in any order.