The Good Sister follows a couple who is working to put their crumbling marriage back together, when the wife receives a letter informing her that she has a long-lost twin sister. First thinking that the new family member will bring the couple closer together, the husband then begins an affair with the sister and discovers that she is treacherous and dangerous.

It may seem like it, but victims of stalking are not just celebrities and those in the public eye; the widely-misunderstood crime affects millions of people in the United States each year, people who are in perpetual fear for their lives; criminal psychologist Dr. Michelle Ward -- a stalking victim herself -- presents stories of the crimes and explores the twisted psychology of those who committed them; victims and their families also recount their personal experiences and provide firsthand insight into effective steps they took to protect themselves; Dr. Ward offers practical tips that viewers can use to keep themselves safe.