Known as the internet's evil twin, the dark web is a place where services offering hit men-for-hire are just a computer click away. "48 Hours" explores the alarming world of murder-for-hire on the mysterious dark web and exposes an international criminal organization in a hunt for a self-described murder mastermind who uses the name Yura. A six-month investigation spans the globe and leads "48 Hours" to information in the U.S. and beyond, about murder plots bought and paid for -- but not yet carried out. Who is Yura? Where is Yura? And can police intervene before someone else gets killed?