About the book: 2021 / The last book of a large-scale crime tetralogy. At the beginning of the 20th century, a wave of unmotivated brutal murders swept across the United States, during which a criminal killed all the residents of the house with blows of an ax at night. These crimes are now being linked to a serial killer who remains unexposed. The author makes an attempt to analyze similar crimes and, based on modern criminological concepts, understand whether they were really committed by one person, and if so, what motivated him.