In this follow-up to Whoever Fights Monsters, a former FBI senior investigator takes us further into the subject of law enforcement's fight against serial killers. He claims to have lived in the monster enough to understand the killers who prey upon modern society and to convey to us the mind of the murderer. The largest part of this book examines in depth the cases in which Ressler has been involved since he retired from the FBI, a period in which he has been consulted by police departments and psychologists all over the world with difficult and mysterious murders, including, in Britain, the Rachel Nickell case.