When a drug sting ends with a dead informant and a missing witness, Wes and Travis are brought in to get to the bottom of things. It turns out the operation was being run by Dan Noone, Travis's swaggering, hard-drinking mentor from his days in the Narcotics division. Hoping to get some insight into the case, Wes enlists the aid of his meticulous old supervisor from Missing Persons, Fred Bandak.
At first, Wes and Travis are eager to work with the men that made them the detectives they are today. However, Bandak's methodical nature starts to grate on Travis, while Wes begins to bristle at Noone's cowboy antics. Soon, both detectives are at odds with one another, neither one willing to admit that their personal mentor may not be all they're cracked up to be.
Meanwhile, as the detectives work their leads, it becomes clear that their missing witness was more than an innocent bystander. But when Bandak theorizes that the shooting could be the work of El Ingeniero, a boogeyman-like legend in the drug world, the two veterans begin to turn on each other. Wes and Travis soon realize that if they want to solve this case, and not end up like their former commanding officers, they may have to put the old lessons aside and do some teaching of their own.