Edward Follis has posed as a buyer for Mexican heroin wholesalers, pretended to be a killer for hire and befriended - then arrested - one of Osama bin Laden's top financiers. He tells Armen Georgian what it takes to be an undercover agent for the US Drug Enforcement Agency, where he worked for 27 years. Follis says it is possible to infiltrate the Islamic State group, but only if the "Dark Art" of going undercover doesn’t become a dying art.
