The Sub focuses on Diana Turney, a substitute teacher left to care for her niece after her sister is imprisoned for the attempted murder of her philandering husband. Haunted by her father's ghost and disturbing repressed memories, Diana discovers she has the power to turn people into their animal totems and proceeds to transform locals into an array of creatures from spiders to pigs. Diana, her cruelty growing in proportion to her power, dismisses a warning from her father that she is destined to kill everyone she loves and continues on a spree of violence and mayhem.