Since ancient Greek times, the Hippocratic Oath has been a vow sworn by doctors in which they swear to practice medicine ethically. Nurses do not take the Hippocratic Oath but at graduation from nursing school they normally take a vow to do their best for their patients. Frequently called the Florence Nightingale Vow it is an adaption of the Hippocratic Oath. The vow contains the mantra of "do not harm." The vow has been updated over time, but the same sentiment remains. This book contains some cases of serial killers, all of whom were female nurses. The crimes of these nurses are heinous and shocking. Why, one might well ask, would someone who had worked and studied hard to be a nurse, want to harm or injure her patients? The unfortunate truth is that a few people become nurses not to aid others but to have attention, control, or power.