THE MASTERMIND

Drugs. Empire. Murder. Betrayal.

By Evan Ratliff

World-class criminals, like world-class writers, are natural obsessives. Alone in their rooms, they both spin endless plots, picking at the details of their projects.

Near the start of “The Mastermind,” Evan Ratliff’s possessed true-crime investigation, there is a stop-and-gawk image of the obsessive outlaw with whom he becomes obsessed: Paul Le Roux, the South African kingpin who gives the work its title. The scene takes place in a thriller-worthy setting — a penthouse condo in Manila, where Le Roux has based his illegal organization. But when one of Ratliff’s sources enters the apartment, he finds the potbellied crime lord in the most unlikely guise: dressed in shorts and flip-flops and perched behind a desk in a room filled with digital servers.

The 300 fever-heated pages that ensue are, in a sense, the author’s agitated — and sometimes self-imperiling — attempt to understand that bizarre tableau and to figure out how Paul Le Roux transformed himself, in the course of 30 years, from a teenage tech geek with a talent for encryption to an international villain with a cadre of mercenaries protecting his interests in everything from Congolese gold to North Korean meth. Ratliff’s journey is not just one of miles logged on the ground, but of incomparable oddness. In his hunt for those who knew Le Roux, he goes to Minnesota, the Philippines, Israel, Brazil and Vietnam, encountering a cast of characters out of a Coen brothers film: a grizzled Canadian security operative, an elderly pharmacist, a target-shooting Filipino cop, a South African hit man and the pseudonymous informant who ran Le Roux’s business in Somalia and later helped the American authorities to capture him.

The narrator fixed on an elusive prey has been a well-worn device at least since “Moby-Dick,” but if there were ever a subject worthy of investigative mania, it is Paul Le Roux. The man was into anything and everything: high-speed yachts, precious metals, plastic explosives, tuna fishing, piracy, Predator drones, Peruvian cocaine and hallucinogens. “He wanted to be the king of his country,” according to the informant who ultimately brought him down. “The big man. Sitting on his fat ass behind a giant desk in his palace.”