The world’s oldest profession is now a thriving black market economy, with an underground workforce that’s just an Internet connection and a phone call away. National Geographic’s Mariana van Zeller journeys to the heart of the American escort industry and uncovers the gritty reality behind the supply and demand of high-end sex work. Television has glamorised it and the internet has made it accessible, thrusting the world’s oldest profession into the 21st Century, but behind closed doors it still remains as dangerous as ever. With many street workers trapped in an increasingly violent and abusive underworld.