here, why don't you have a seat right over there by the bar? did you enjoy the drink? >> it is all part of the "dateline" investigation into on line sex predators. men from all walks of life show up. a respected doctor. >> maybe we can go for a ride later. >> you bet. >> reporter: and a carpenter who gave us the most revealing confession we have ever heard. >> is there a part of you who wishes the 13-year-old girl was here? >> if the 13-year-old girl looked like your friend there, i don't know. >> but nearly all of them say they had no plans to have sex with a minor. >> so we probably have four guys. >> we have hired the on-line watch dog group, experts who pretend to be kids on line. for this operation, the volunteers go into local california chat rooms, posing as 12 and 13-year-olds and wait to be contacted by an adult.