The "dark web" is where online services offering illicit drugs and hit men for hire are just a click away. The murder of a mother in the Midwest led "48 Hours" correspondent Peter Van Sant into the shadowy world of the dark web. His six-month investigation uncovered murder plots that were paid for, but not yet carried out. "48 Hours" alerted authorities around the world, hoping to save lives. Van Sant joins "CBS This Morning" to preview his report. Watch "Click for a Killer" in the two-hour season premiere of “48 Hours” on Saturday, 9/8c on CBS.