This book provides extensive information on pedophilia (sexual interest in the prepubescent body age), hebephilia (sexual interest in the early-pubescent body age) and sexual offenses against children, i.e., the various forms of child sexual abuse, including the use of child sexual abuse images, along with the current state of knowledge concerning offender groups. The book makes it clear that pedophilia or hebephilia do not inevitably lead to offenses against children - that there are those who keep their desires in their fantasies and do not act them out on the behavioral level. The World Health Organization classifies pedophilia as a mental disorder. It can be safely assumed that many pedophile men in a given community live their lives, unrecognized and adamant about hiding their sexual drives from society and from themselves, and who are genuinely motivated not to act upon their sexual fantasies. The numbers of exactly this particular group of pedophilically inclined non-offenders can be increased by preventive therapeutic measures. For this purpose, two treatment programs have been developed at the Institute of Sexology and Sexual Medicine at the Charité-Universitätsmedizin Berlin (University Clinic) since the initiation of the Prevention Project Dunkelfeld in 2005 - First, the project involving adult participants (Berlin Dissexuality Therapy: BEDIT) and later, another for adolescents (BEDIT-A), who find themselves attracted to children. Both program manuals are completely integrated into this work, which reflects 15 years of assessment and treatment experience.

Klaus M. Beier studied medicine (M.D. 1986) and philosophy (Ph.D. 1988). He is a specialized physician for psychosomatics and psychotherapy and since 1996 head of the Institute of Sexology and Sexual Medicine at the Charité - Universitätsmedizin Berlin (University Clinic). He is in charge of the undergraduate training of medical school students in sexual medicine (over 600 p.a.) as well as the post-graduate training for physicians and psychologists in this field. He is also responsible for the Outpatient Clinic of the Institute which offers assessment and treatment for the full range of sexual disorders and gender dysphoria. His main focus in research is the prevention of child sexual abuse. The goal is to encourage self-identified undetected pedophiles to seek professional help in order to avoid committing child sexual abuse or the use of child sexual exploitation material. For this purpose, in 2005 he initiated the 'Prevention Project Dunkelfeld' which has now extended to 10 additional locations all over Germany (www.dont-offend.org) and is being financed by the German insurance system for the next 5 years. Furthermore, since 2014, Prof. Beier has expanded the prevention approach to recruit juveniles aged between 12 and 18, who display sexually deviant behavior towards children and/or fantasies about the body image of children (www.just-dreaming-of-them.org). In India, in 2015,  he started  a Program for Primary Prevention of Sexual Violence (www.pppsv.org) and developed culturally adapted prevention measurements to prevent sexual violence against women in India dealing with male sexual aggression towards females. 2017 he started the worldwide useable internet-based self-management tool 'Troubled Desire' for assessment and treatment in cases of pedophilia to prevent child sexual abuse, the use of child sexual abuse images   and to arrange contacts to therapists adjusted to the particular laws in each country, even those with mandatory reporting laws (www.troubled-desire.com). Regarding these efforts in the sense of service to his country, in 2017, he was awarded the Order of Merit from the Federal Republic of Germany. 

As the latest extension of the prevention approach, in 2020, he established remote assessment and treatment for this special indication group focusing on lowering the threshold for receiving support in terms of preventive measures.