Mexican Brown by Chet Cunningham
Dirty Dope. It happens all the time. Deaths from overdoses of heroin. Now it was more than that. Narcotics agents muttered that the Mexican Brown heroin coming in across the border was some strange mix dirty...and deadly. Mark Hardin has a line on the hot horse, but he has to move fast and find a way to beat the smugglers to the border before they can sneak the stuff into the country. If he fails, he'll be in one helluva fix!