Divorce gradually depletes Marcella, all judicial processes affect the mental and police work. The woman is unable to carry out the duties of detective, focusing all attention on trying to keep custody of her daughter. The referee decides to separate the child from the mother, sending the girl to study in a boarding school.
Despite family problems, the girl needs to go back to police work. The manual instructs the investigation of several cases, among which one can trace a common thread. The detective recalls that when she was trying to solve similar crimes, but are unable to get started before catching criminals.