Dr Garrison is a doctor at the hospital in Maple Springs, where a series of gruesome deaths are occurring. At the scene of the crimes, some witnesses report seeing a young girl. When Dean sees the girl, who is obviously a spirit, she indicates by leaving behind an apple, that she was poisoned by her step-mother.
When Sam and Dean find out that Dr Garrison has a daughter, Callie, who has been in a vegetative state since the age of eight, to whom he reads fairy tale stories, they deduce that she is behind the deaths. Sam has to convince Dr Garrison of this, and when he finally accepts the truth, her spirit is at rest.