Four criminal businesses and four dangerous maniacs, that without sympathy and pricks of conscience calmly put to death other people. Who were they to the conclusion and why decided on murders? In a tiny room for interrogations the former agent of FBI John Douglas speaks with each of them and tries to understand how crimes are conceived. Analysing materials of businesses, biographies and psychological state of killers, he tells about that, how they think, and that moves by them.