Three casinos. Three corpses. Three days. After a string of brutal murders in Las Vegas, Cassie Hobbs and The Naturals come to help with the investigation. But even a team with unique profiling abilities finds themselves baffled by these murders: unlike most serial killers, this one kills differently each time. All the victims were killed in public places, but the killer did not appear on any surveillance footage. And on the wrists of each victim there is a tattoo - a sequence of numbers. There is a code in these numbers - and the closer The Naturals get to solving the mystery, the more dangerous the case becomes. At the same time, Cassie is faced with an equally dangerous, but much more bitter mystery. For the first time in many years, there is a breakthrough in her mother's case. There are more and more personal problems, tension in the team is growing, the chances of Cassie and the Naturals winning are slim - and the choice ahead of them is impossible.