The Threshold Institute specializes in pain. Institute director Lady Olivia fondly remembers a series of tests run on girls who have experienced a numbing of sensation due to brutal treatment at the hands of a family member.

Charlie was spanked senseless by her stepfather and now wants to feel pain again on the road to recovery. Olivia understands, and spanks and flogs her as part of her unorthodox therapy. She also suspends her by wrists and ankles, uses tack gloves, clothespins and a rather nasty pinwheel.

Next, rival siblings Chloe and Cleo are hauled down to the dungeon and flogged, clamped, spanked, whipped and humiliated by Lady O in an effort to bring them back to painful reality.