Nick Kowalski has proudly worn the badge of the Houston Police Department for close to four decades.

At 60, the tough, uncompromising member of the Houston PD Gang Division is showing no signs of slowing down, but Kowalski's world is thrown asunder when long-time partner Bill Riggs is gunned down in front of his eyes during a raid on a drug deal. In the aftermath of Riggs' senseless slaying, he's partnered with Diana Zhou, a young, very naïve detective whose father is one of the wealthiest men in Houston. Using her connections to Houston's Chinese community, Zhou helps Kowalski track down the triad leader who murdered Riggs.