The Killer Inside: The Ruth Finley Story follows Ruth and her husband, Ed’s, tranquil life in Wichita, Kansas which is suddenly turned upside down when Ed suffers a heart attack. As Ed fights for his life in the hospital, Ruth starts to receive mysterious threats, leaving her in a state of panic. With the city held hostage by the terror of the BTK killer, Ruth finds herself enveloped in paranoia, convinced that she will be the next victim, as the menacing phone calls escalate into chilling letters.