Two for the Show by Jonathan Stone

The main character, Chas, is a loner with no family or friends to speak of and a relationship to which he give very little of himself. Instead, his main focus in life is his job. It's a job that he has been devoted to for 20 years, but it's also a job that he can tell no one about. His life is one of secrets until one day when his life is thrown a curve ball. You see, Chas works for Archer Wallace, a.k.a. Wallace the Amazing. Wallace is a legendary performer in Las Vegas who can scan his audience, pick a person out at random, and tell him (or her) amazing details about his life. Things that would be impossible for the everyday person to know, but Wallace has the mental abilities to do this, at least that's what he says. In reality, he has an amazing memory, but Chas is the one supplying him with the amazing details. He scours the Internet and logs into private databases to cull as much information he can for his employer. Then, one day, Wallace calls on an audience member who throws the whole charade for a loop. That person isn't who he says he is. He knows it and so does Wallace, but what he wants is to force Wallace to pay him to keep quiet. Thus begins a roller coaster of events. With this interesting setup, the further you get into the story, the more you wonder how it's going to end.