The smuggler at the center of the story discovers that his Colombian suppliers are routinely packing all different strains of marijuana together, with a single bale containing everything from low-grade weed to the Santa Marta Gold that American potheads would pay top-dollar for. To the Colombians there's no difference between one strain of weed and another, but the smuggler knows to the American buyer it can mean a huge difference in price. So he works with them to start separating the different strains and buys every bale of Santa Marta Gold he can get his hands on, becoming the first smuggler who can bring his customers a consistent, reliable supply of the Good Stuff. Which of course makes him a fortune, and which of course leads to all sorts of other problems.

(Sabbag's book is a fantastic read, I recommend it highly. And if you want a shorter-form introduction to the story, here's an interview with the smuggler in question after his lawbreaking days were over: https://www.styleweekly.com/richmond/allen-longs-days-as-an-...)