The high profile kidnapping of a billionaire's son and the murder of his girlfriend while they participated in a scavenger hunt game forces the CSIs to investigate the crimes in the middle of a ransom situation. Mac realizes the ransom drop is a distraction for the assailants' actual plan to extract money directly from the source, the billionaire, and when their plan is foiled, the perps demand double the ransom. However, the CSIs land a breakthrough in the case when they link DNA evidence found on the murdered girlfriend's dress to a NY macabre souvenir shop specializing in serial killers’ paraphernalia. When the team realizes their perps are on the customer list, they identify and apprehend the kidnappers and rescue the billionaire's son. The perps later confess to being serial robbers who got in over their heads after they accidentally killed the girlfriend, who assumed they were part of the scavenger hunt and pulled a fake gun on them. Finally, Mac More...meets up with an old friend through his online profile page.