The plot of this book is based on the concept of cellular memory. Cellular memory is a hypothesis that memories can be stored outside the brain. The cellular memory hypothesis states that these memories are stored in all the cells of human bodies. The idea that non-brain tissues can have memories is also believed by some individuals who have received organ transplants, though this is also considered impossible.
When Jenna tells Vanessa, her therapist, about what she feels, she explains her behaviour as a result of Secondary Traumatic Stress (STS). Compassion fatigue, also known as secondary traumatic stress (STS), is a condition characterised by a gradual lessening of compassion over time. It is common among individuals that work directly with trauma victims such as, therapists (paid and unpaid), nurses, teachers, psychologists, police officers, first responders, animal welfare workers, health unit coordinators and anyone who helps out others. Sufferers can exhibit several symptoms including hopelessness, a decrease in experiences of pleasure, constant stress and anxiety, sleeplessness or nightmares, and a pervasive negative attitude. This can have detrimental effects on individuals, both professionally and personally, including a decrease in productivity, the inability to focus, and the development of new feelings of incompetency and self-doubt.