The once star profiler for the FBI, Doug ONeal, who has been able to capture the greatest of serial killers, rapists, and criminals, comes back to San Francisco to find the worst of them. Because of this killer's background, the FBI has never even known he existed. Doug has only suspected that he exists. The FBI puts together a task force with the San Francisco police, Anne Borges, and Jeff Shinn to hunt down this suspect to prevent any more deaths. The police are always looking for the suspect, but are they looking in the right place? While this killer evolves and develops his methods, the members of the task force learn more about each other and themselves, leading their own lives down different paths and growing as they join each other in pursuit. So near to retirement and after so many years of chasing monsters, it's a wonder Doug has not gone off the deep end himself. When the ordinary go off the deep end and become a monster, they are an ordinary monster, but this is not the case when the extraordinary become a monster.